An experiment has three distinct outcomes, A, B and C.
Outcome A occurs 50% of the time. Outcome B occurs 23% of the time.
What is the expected number of times outcome C would occur if the experiment is conducted 500 times?
- 115
- 135
- 250
- 365
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An experiment has three distinct outcomes, A, B and C.
Outcome A occurs 50% of the time. Outcome B occurs 23% of the time.
What is the expected number of times outcome C would occur if the experiment is conducted 500 times?
`text(B)`
`text(Expectation of outcome)\ C`
`= 1 – 0.5 – 0.23`
`= 0.27`
`:.\ text(Expected times)\ C\ text(occurs)`
`= 0.27 xx 500`
`= 135`
`=>\ text(B)`
Which graph best represents the equation `y = x^2-2`?
| A. | B. | ||
| C. | D. |
`A`
`y = x^2-2`
`ytext(-intercept) = -2\ \ \ (text(when) = 0)`
`text(Quadratic is positive with vertex at)\ \ y = -2`
`=>A`
A survey asked the following question.
'How many brothers do you have?'
How would the responses be classified?
`text(C)`
`text(The number of brothers a person has is)`
`text(an exact whole number.)`
`:.\ text(Classification is numerical, discrete.)`
`=>\ text(C)`
Two secants from the point `C` intersect a circle as shown in the diagram.
What is the value of `x`? (2 marks)
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`4`
`text(Using formula for intercepts of intersecting secants:)`
| `x (x + 2)` | `= 3 (3 + 5)` |
| `x^2 + 2x` | `= 24` |
| `x^2 + 2x – 24` | `= 0` |
| `(x + 6) (x – 4)` | `= 0` |
| `:. x` | `= 4 \ \ \ (x > 0)` |
Consider the polynomial `P(x) = x^3-2x^2-5x + 6`.
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i. `P(1) = 1-2-5 + 6 = 0`
`:. x=1\ \ text(is a zero)`
ii. `text{Using part (i)} \ => (x-1)\ text{is a factor of}\ P(x)`
`P(x) = (x-1)*Q(x)`
`text(By long division:)`
| `P(x)` | `= (x-1) (x^2-x-6)` |
| `= (x-1) (x-3) (x + 2)` |
`:.\ text(Other zeroes are:)`
`x = -2 and x = 3`
A solid is made up of a sphere sitting partially inside a cone.
The sphere, centre `O`, has a radius of 4 cm and sits 2 cm inside the cone. The solid has a total height of 15 cm. The solid and its cross-section are shown.
Using the formula `V=1/3 pi r^2h` where `r` is the radius of the cone's circular base and `h` is the perpendicular height of the cone, find the volume of the cone, correct to the nearest cm³? (3 marks)
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`113\ text{cm}^3`
`V = 1/3 xx text(base of cone × height)`
`text(Consider the circular base area of the cone,)`
`text(Find)\ x\ \ text{(using Pythagoras):}`
| `x^2` | `= 4^2-2^2 = 16-4 = 12` |
| `x` | `= sqrt12\ text(cm)` |
| `:. V` | `= 1/3 xx pi xx (sqrt12)^2 xx (15-6)` |
| `= 1/3 xx pi xx 12 xx 9` | |
| `= 113.097…` | |
| `= 113\ text{cm}^3\ text{(nearest cm}^3 text{)}` |
The triangle `ABC` is isosceles with `AB = AC` and the size of `/_BAC` is `x^@`.
Points `D` and `E` are chosen so that `Delta ABC, Delta ACD` and `Delta ADE` are congruent, as shown in the diagram.
Find the value of `x` for which `AB` is parallel to `ED`, giving reasons. (3 marks)
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`x = 36`
Which polynomial is a factor of `x^3-5x^2 + 11x-10`?
`A`
| `f(2)` | `= 2^3-5*2^2 + 11*2-10` |
| `= 8-20 + 22 – 10` | |
| `= 0` |
`:. (x-2)\ text(is a factor)`
`⇒ A`
Find the domain of the function `f(x) = sqrt (3-x)`. (2 marks)
`x <= 3 or (-oo,3].`
`text(Domain of)\ \ f(x) = sqrt (3-x)`
| `3-x` | `>= 0` |
| `x` | `<= 3` |
`text(Note domain can also be expressed as:)\ \ (-oo,3]`
The region enclosed by `y = 4 - x,\ \ y = x` and `y = 2x + 1` is shaded in the diagram below.
Which of the following defines the shaded region?
| A. | `y <= 2x + 1, qquad` | `y <= 4-x, qquad` | `y >= x` |
| B. | `y >= 2x + 1, qquad` | `y <= 4-x, qquad` | `y >= x` |
| C. | `y <= 2x + 1, qquad` | `y >= 4-x, qquad` | `y >= x` |
| D. | `y >= 2x + 1, qquad` | `y >= 4-x, qquad` | `y >= x` |
`A`
`text(Consider)\ \ y = 2x + 1,`
`text(Shading is below graph)`
`=> y <= 2x + 1`
`text(Consider)\ \ y = 4-x,`
`text(Shading is below graph)`
`=> y <= 4-x`
`=> A`
Which expression is equal to `3x^2-x-2`?
`D`
`3x^2-x-2= (3x + 2) (x-1)`
`=> D`
What is the gradient of the line `2x + 3y + 4 = 0`?
`A`
| `2x + 3y + 4` | `= 0` |
| `3y` | `= -2x-4` |
| `y` | `= -2/3 x-4/3` |
| `:.\ text(Gradient)` | `= -2/3` |
`=> A`
A movie theatre has 200 seats. Each ticket currently costs $8.
The theatre owners are currently selling all 200 tickets for each session. They decide to increase the price of tickets to see if they can increase the income earned from each movie session.
It is assumed that for each one dollar increase in ticket price, there will be 10 fewer tickets sold.
A graph showing the relationship between an increase in ticket price and the income is shown below.
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Calculate the profit earned by the theatre owners when the income earned from a session is maximised. (2 marks)
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i. `text(Graph is highest when increase = $6)`
`:.\ text(Ticket price)\ = 8 + 6= $14`
ii. `text(Solution 1)`
`text(Tickets sold)\ =200-(4 xx 10)=140`
`text(Solution 2)`
`text(Tickets)\ = text(max income)/text(ticket price) = 1960/14= 140`
iii. `text{Cost}\ = 140 xx $2 + $500= $780`
`:.\ text(Profit when income is maximised)`
`= 1960-780`
`= $1180`
Jamal surveyed eight households in his street. He asked them how many kilolitres (kL) of water they used in the last year. Here are the results.
`220, 105, 101, 450, 37, 338, 151, 205`
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| a. | `text(Mean)` | `= (220 + 105 + 101 + 450 + 37 + 338 + 151 + 205) ÷ 8` |
| `= 200.875` |
| b. | `text(Std Dev)` | `= 127.357…\ \ text{(by calc)}` |
| `= 127.4\ \ text{(1 d.p.)}` |
A sewer pipe needs to be placed into the ground so that it has a 2° angle of depression. The length of the pipe is 15 000 mm.
How much deeper should one end of the pipe be compared to the other end? Answer to the nearest mm. (2 marks)
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`523\ text{mm (nearest mm)}`
`text(Let)\ \ x = text(depth needed)`
| `sin 2^@` | `= x/(15\ 000)` |
| `x` | `= 15\ 000 xx sin 2^@` |
| `= 523.49…` | |
| `= 523\ text{mm (nearest mm)}` |
In the circle, centre `O`, the area of the quadrant is 100 cm².
What is the arc length `l`, correct to one decimal place?
`C`
`text(Find)\ r:`
| `text(Area)` | `= 1/4 pir^2` |
| `100` | `= 1/4 pir^2` |
| `r^2` | `= 400/pi` |
| `:. r` | `= 11.283…\ text(cm)` |
| `text(Arc length)` | `= theta/360 xx 2pir` |
| `= 90/360 xx 2pi xx 11.283…` | |
| `= 17.724…` | |
| `= 17.7\ text(cm)` |
`=> C`
The faces on a twenty-sided die are labelled $0.05, $0.10, $0.15, … , $1.00.
The die is rolled once.
What is the probability that the amount showing on the upper face is more than 50 cents but less than 80 cents?
A. `1/4`
B. `3/10`
C. `7/20`
D. `1/2`
`A`
`text(Possible faces that satisfy are:)`
`55text(c),60text(c),65text(c),70text(c),75text(c)`
| `:.\ text(Probability)` | `= 5/20` |
| `= 1/4` |
`=>A`
Which of the data sets graphed below has the largest positive correlation coefficient value?
| A. | B. | ||
| C. | D. |
\(C\)
\(\text{Largest positive correlation occurs when both variables move}\)
\(\text{in tandem. The tighter the linear relationship, the higher the}\)
\(\text{correlation.}\)
\(\Rightarrow C\)
\(\text{(Note that B is negatively correlated)}\)
A new car was bought for $19 900 and one year later its value had depreciated to $16 300.
What is the approximate depreciation, expressed as a percentage of the purchase price?
`A`
| `text(Net Depreciation)` | `= 19\ 900-16\ 300` |
| `= $3600` |
| `:. %\ text(Depreciation)` | `= 3600/(19\ 900) xx 100` |
| `= 18.09…text(%)` |
`=>A`
What is the value of `x` in the equation `(5-x)/3 = 6`?
`A`
| `(5-x)/3` | `= 6` |
| `5-x` | `= 18` |
| `x` | `= 5-18` |
| `= -13` |
`=>A`
Tom earns a weekly wage of $1025. He also receives an additional allowance of $87.50 per day when handling toxic substances.
What is Tom’s income in a fortnight in which he handles toxic substances on 5 separate days?
`D`
| `text(Fortnightly wage)` | `= 2 xx 1025` |
| `= $2050` |
| `text(Allowances)` | `= 5 xx 87.50` |
| `= $437.50` |
| `:.\ text(Income)` | `= 2050 + 437.50` |
| `= $2487.50` |
`=>D`
In a survey of 200 randomly selected Year 12 students it was found that 180 use social media.
Based on this survey, approximately how many of 75 000 Year 12 students would be expected to use social media?
A. 60 000
B. 67 500
C. 74 980
D. 75 000
`B`
| `text(Expected number)` | `= 180/200 xx 75\ 000` |
| `= 67\ 500` |
`=> B`
The graph shows the relationship between infant mortality rate (deaths per 1000 live births) and life expectancy at birth (in years) for different countries.
What is the life expectancy at birth in a country which has an infant mortality rate of 60?
\(A\)
In the diagram, `O` is the centre of the circle `ABC`, `D` is the midpoint of `BC`, `AT` is the tangent at `A` and `∠ATB = 40^@`.
What is the size of the reflex angle `DOA`?
`C`
| `/_ ODT` | `=90^@\ \ text{(line through centre bisecting chord)}` |
| `/_OAT` | `= 90^@\ \ text{(tangent ⊥ to radius at point of contact)}` |
| `/_ DOA` | `= 360-(90 + 90 + 40)` |
| `= 140^@` |
| `:. DOA\ \ text{(reflex)}` | `= 360-140` |
| `= 220^@` |
`=> C`
What is the remainder when `2x^3-10x^2 + 6x + 2` is divided by `x-2`?
`B`
| `P(2)` | `= 2 · 2^3-10 · 2^2 + 6 · 2 + 2` |
| `= -10` |
`=> B`
Write `log 2 + log 4 + log 8 + … + log 512` in the form `a log b` where `a` and `b` are integers greater than `1.` (2 marks)
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`45 log 2`
`log 2 + log 4 + log 8 + … + log 512`
`= log 2^1 + log 2^2 + log2^3 + … + log 2^9`
`= log 2 + 2 log 2 + 3 log 2 + … + 9 log 2`
`= 45 log 2`
A school playground consists of part of a circle, with centre `O`, and a rectangle as shown in the diagram. The radius `OB` of the circle is 45 m, the width `BC` of the rectangle is 20 m and `AOB` is 100°.
What is the area of the whole playground, correct to the nearest square metre? (5 marks)
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`6971\ text{m² (nearest m²)}`
`text(In)\ DeltaOEB,`
| `sin50^@` | `= (EB)/45` |
| `EB` | `= 45 xx sin50^@` |
| `= 34.47…` |
| `:. AB` | `= 2 xx 34.47…` |
| `= 68.944\ \ (text(3 d.p.))` |
| `cos50^@` | `= (OE)/45` |
| `:. OE` | `= 45 xx cos50^@` |
| `= 28.925\ \ (text(3 d.p.))` |
`text(Area of)\ DeltaOAB`
`= 1/2 xx AB xx OE`
`= 1/2 xx 68.944 xx 28.925`
`= 997.12\ text(m²)`
| `text(Area)\ ABCD` | `= 20 xx 68.944` |
| `= 1378.88\ text(m²)` |
`text(Area of major sector)\ OAB`
`= pi xx 45^2 xx 260/360`
`= 4594.58\ text(m²)`
`:.\ text(Area of playground)`
`= 997.12 + 1378.88 + 4594.58`
`= 6970.58`
`= 6971\ text{m² (nearest m²)}`
A company makes large marshmallows. They are in the shape of a cylinder with diameter 5 cm and height 3 cm, as shown in the diagram.
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A cake is to be made by stacking 24 of these large marshmallows and filling the gaps between them with chocolate. The diagrams show the cake and its top view. The shading shows the gaps to be filled with chocolate.
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| a. | `V` | `= pir^2h` |
| `= pi xx 2.5^2 xx 3` | ||
| `= 58.904…` | ||
| `= 58.9\ text{cm³ (1 d.p.)}` |
| b. | ![]() |
`text(Volume of rectangle)`
`= 15 xx 10 xx 6`
`= 900\ text(cm)^3`
`text(Volume of marshmallows in rectangle)`
`= 6 xx 2 xx 58.9`
`= 706.8\ text(cm)^3`
`:.\ text(Volume of chocolate)`
`= 900-706.8`
`= 193.2`
`= 193\ text{cm}^3 \ text{(nearest cm}^3 text{)}`
Theo is completing his tax return. He has a gross salary of $82 521 and income from a rental property totalling $10 920. He is claiming $13 420 in allowable deductions.
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\begin{array} {|l|l|}
\hline
\rule{0pt}{2.5ex}\textit{ Taxable income}\rule[-1ex]{0pt}{0pt} & \textit{ Tax payable}\\
\hline
\rule{0pt}{2.5ex}\text{\$0 – \$18 200}\rule[-1ex]{0pt}{0pt} & \text{Nil}\\
\hline
\rule{0pt}{2.5ex}\text{\$18 201 – \$37 000}\rule[-1ex]{0pt}{0pt} & \text{19 cents for each \$1 over \$18 200}\\
\hline
\rule{0pt}{2.5ex}\text{\$37 001 – \$80 000}\rule[-1ex]{0pt}{0pt} & \text{\$3572 plus 32.5 cents for each \$1 over \$37 000}\\
\hline
\rule{0pt}{2.5ex}\text{\$80 001 – \$180 000}\rule[-1ex]{0pt}{0pt} & \text{\$17 547 plus 37 cents for each \$1 over \$80 000}\\
\hline
\rule{0pt}{2.5ex}\text{\$180 001 and over}\rule[-1ex]{0pt}{0pt} & \text{\$54 547 plus 45 cents for each \$1 over \$180 000}\\
\hline
\end{array}
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a. `text(Taxable income)`
`= 82\ 521 + 10\ 920-13\ 420`
`= $80\ 021`
b. `text(Tax payable)`
`= 17\ 547 + (80\ 021-80\ 000) xx 0.37`
`= $17\ 554.77`
c. `text(Total tax payable)`
`= 17\ 554.77 + 1600.42`
`= $19\ 155.19`
`text(Tax paid > tax payable)`
| `:.\ text(Refund)` | `= 20\ 525-19\ 155.19` |
| `= $1369.81` |
Jenny earns a yearly salary of $63 752. Her annual leave loading is 17.5% of four weeks pay.
Calculate her total pay for her four weeks of annual leave. (3 marks)
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`$5762.20`
`text(4 weeks’ normal pay)`
`= 4/52 xx 63\ 752`
`= $4904`
`:.\ text(Annual leave pay)`
`= 4904(1 + 17.5/100)`
`= $5762.20`
Simplify `(8x^4y)/(24x^3y^5)`. (2 marks)
`x/(3y^4)`
| `(8x^4y)/(24x^3y^5)` | `=(x^((4-3))y^((1-5)))/3` | |
| `=(xy^(-4))/3` | ||
| `=x/(3y^4)` |
Which of the following correctly expresses `Q` as the subject of `e = iR + Q/C`?
`=> B`
| `e` | `= iR + Q/C` |
| `Q/C` | `= e-iR` |
| `:. Q` | `= C(e-iR)` |
| `= Ce-CiR` |
`=> B`
A group of 485 people was surveyed. The people were asked whether or not they smoke. The results are recorded in the table.
A person is selected at random from the group.
What is the approximate probability that the person selected is a smoker OR is male?
`=> C`
`P(text(Smoker or a male))`
`= (text(Total males + female smokers))/(text(Total surveyed))`
`= (264 + 68)/485`
`= 0.684…`
`=> C`
The box-and-whisker plots show the results of a History test and a Geography test.
In History, 112 students completed the test. The number of students who scored above 30 marks was the same for the History test and the Geography test.
How many students completed the Geography test?
`=> C`
`text{In History} \ => \ text{Q}_3 = 30\ \text{marks}`
`:.\ text{Scoring over 30}\ = 25text(%) xx 112 = 28\ \text{students}`
`text{In Geography} \ => \ text{Median}\ = 30\ \text{marks}`
`:.\ text{Students completing Geography}\ =2 xx 28 = 56\ \text{students}`
`=> C`
Isabella works a 35-hour week and is paid at an hourly rate of $18. Any overtime hours worked are paid at time-and-a-half. In a particular week, she earned $1008.
How many hours in total did Isabella work in this week to earn this amount?
`=> C`
`text(Let)\ \ X=\ text(number of extra hours worked.)`
| `text(Total wage)` | `= 35 xx 18 + X xx 27` |
| `1008` | `= 630 + 27X` |
| `27X` | `=378` |
| `X` | `=14` |
`:.\ text(Total hours worked)\ =35+14=49`
`=> C`
A soccer referee wrote down the number of goals scored in 9 different games during the season.
`2, \ 3, \ 3, \ 3, \ 5, \ 5, \ 8, \ 9, \ ...`
The last number has been omitted. The range of the data is 10.
What is the five-number summary for this data set?
`=> A`
`text{Since range is 10} \ => \ text{Last data point = 12}`
`text{Q}_1 = 3`
`text{Q}_3 = (8 + 9)/2 = 8.5`
`text(Median = 5)`
`=> A`
The width (`W`) of a river can be calculated using two similar triangles, as shown in the diagram.
What is the approximate width of the river?
`=> A`
`text{Triangles are similar (equiangular)}`
`text(Using similar ratios:)`
| `W/(7.1)` | `= 20.3/8.1` |
| `:. W` | `= (20.3 xx 7.1)/8.1` |
| `= 17.79…` |
`=> A`
The graph shows a line which has an equation in the form `y = mx + c`.
Which of the following statements is true?
`=> A`
`m` is the gradient and the line slopes to the right so `m` is positive.
`c` is the `y`-intercept which is negative.
`:.\ m` is positive and `c` is negative.
`=> A`
A container is in the shape of a triangular prism which has a capacity of 12 litres. The area of the base is 240 cm².
What is the distance, `h`, between the two triangular ends of the container?
`=> D`
`text{1 mL = 1 cm}^3\ \ =>\ \ text{1 L = 1000 cm}^3`
| `text(Volume)` | `= Ah` |
| `12\ 000` | `= 240 xx h` |
| `h` | `= (12\ 000)/240` |
| `= 50\ text(cm)` |
`=> D`
Which set of data is classified as categorical and nominal?
`A`
`text(Categorical and nominal data is)`
`text(qualitative and not ordered.)`
`=> A`
Which expression is equivalent to `2(3x-4) + 2`?
`C`
`2(3x-4) + 2`
`= 6x-8 + 2`
`= 6x-6`
`=> C`
What is 208.345 correct to two significant figures?
`B`
`208.345 = 210\ (2\ text(sig. fig.))`
`=> B`
The polynomial `P(x) = x^2 + ax + b` has a zero at `x = 2`. When `P(x)` is divided by `x + 1`, the remainder is `18`.
Find the values of `a` and `b`. (3 marks)
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`a = -7\ \ text(and)\ \ b = 10`
`P(x) = x^2 + ax + b`
`text(S)text(ince there is a zero at)\ \ x = 2,`
| `P(2)` | `=0` | |
| `2^2 + 2a + b` | `= 0` | |
| `2a + b` | `= -4` | `…\ (1)` |
`P(-1) = 18,`
| `(-1)^2-a + b` | `= 18` | |
| `-a + b` | `= 17` | `…\ (2)` |
`text(Subtract)\ \ (1)-(2),`
| `3a` | `= -21` |
| `a` | `= -7` |
`text(Substitute)\ \ a = -7\ \ text{into (1),}`
| `2(-7) + b` | `= -4` |
| `b` | `= 10` |
`:.a = -7\ \ text(and)\ \ b = 10`
Find the equation of the line that passes through the point `(1, 3)` and is perpendicular to `2x + y + 4 = 0`. (2 marks)
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`x-2y + 7 = 0`
| `2x + y + 4` | `= 0` |
| `y` | `= -2x-4` |
`=>\ text(Gradient) = -2`
`:. text(⊥ gradient) = 1/2\ \ \ (m_1 m_2=-1)`
`text(Equation of line)\ \ m = 1/2, \ text(through)\ (1, 3):`
| `y-y_1` | `= m (x-x_1)` |
| `y-3` | `= 1/2 (x-1)` |
| `y` | `= 1/2 x + 5/2` |
| `2y` | `= x + 5` |
| `:. x-2y + 5` | `= 0` |
Consider the polynomials `P(x) = x^3-kx^2 + 5x + 12` and `A(x) = x - 3`.
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| i. | `P(x)` | `= x^3-kx^2 + 5x + 12` |
| `A(x)` | `= x-3` |
`text(If)\ P(x)\ text(is divisible by)\ A(x)\ \ =>\ \ P(3) = 0`
| `3^3-k(3^2) + 5 xx 3 + 12` | `= 0` |
| `27-9k + 15 + 12` | `= 0` |
| `9k` | `= 54` |
| `:.k` | `= 6\ \ …\ text(as required)` |
ii. `text(Find all roots of)\ P(x)`
`P(x)=(x-3)*Q(x)`
`text{Using long division to find}\ Q(x):`
| `:.P(x)` | `= x^3-6x^2 + 5x + 12` |
| `= (x-3)(x^2-3x − 4)` | |
| `= (x-3)(x-4)(x + 1)` |
`:.\ text(Zeros at)\ \ \ x = -1, 3, 4`
Two secants from the point `P` intersect a circle as shown in the diagram.
What is the value of `x`?
`B`
`text{Property: products of intercepts of secants from external point are equal}`
| `x(x + 3)` | `= 4(4 + 6)` |
| `x^2 + 3x` | `= 40` |
| `x^2 + 3x-40` | `= 0` |
| `(x-5)(x + 8)` | `= 0` |
`:.x = 5,\ \ (x>0)`
`=>B`
What is the remainder when `x^3-6x` is divided by `x + 3`?
`A`
| `text(Remainder)` | `= P(-3)` |
| `= (-3)^3-6(-3)` | |
| `= -27 + 18` | |
| `= -9` |
`=> A`
The formula `C = 5/9 (F-32)` is used to convert temperatures between degrees Fahrenheit `(F)` and degrees Celsius `(C)`.
Convert 3°C to the equivalent temperature in Fahrenheit. (2 marks)
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`37.4\ text(degrees)\ F`
| `C` | `= 5/9(F-32)` |
| `F-32` | `= 9/5C` |
| `F` | `= 9/5C + 32` |
`text(When)\ \ C = 3,`
| `F` | `= (9/5 xx 3) + 32` |
| `= 37.4\ text(degrees)\ F` |
Ariana’s parents have given her an interest‑free loan of $4800 to buy a car. She will pay them back by paying `$x` immediately and `$y` every month until she has repaid the loan in full.
After 18 months Ariana has paid back $1510, and after 36 months she has paid back $2770.
This information can be represented by the following equations.
`x + 18y = 1510`
`x + 36y = 2770`
i.
`:.\ text(Solution is)\ \ x = 250, \ y = 70`
ii. `text(Let)\ \ A = text(the amount paid back after)\ n\ text(months)`
`A = 250 + 70n`
`text(Find)\ n\ text(when)\ A = 4800`
| `250 + 70n` | `= 4800` |
| `70n` | `= 4550` |
| `n` | `= 65` |
`:.\ text(It will take Ariana 65 months to repay)`
`text(the loan in full.)`
At a particular time during the day, a tower of height 19.2 metres casts a shadow. At the same time, a person who is 1.65 metres tall casts a shadow 5 metres long.
What is the length of the shadow cast by the tower at that time? (2 marks)
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`58\ text{m}`
`text(Both triangles have right angles and a common)`
`text(angle to the ground.)`
`:.\ text{Triangles are similar (equiangular)}`
`text(Let)\ x =\ text(length of tower shadow)`
| `x/5` | `= 19.2/1.65\ \ text{(corresponding sides of similar triangles)}` |
|
| `x` | `= (5 xx 19.2)/1.65` | |
| `= 58.1818…` | ||
| `= 58\ text{m (nearest m)}` |
Approximately 71% of Earth’s surface is covered by water. Assume Earth is a sphere with a radius of 6400 km.
Calculate the number of square kilometres covered by water. (2 marks)
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`3.7 xx 10^8\ text(km²)\ \ text{(nearest km²)}`
`text(Surface area of Earth)`
`= 4pir^2`
`= 4pi xx 6400^2`
`:.\ text(Surface covered by water)`
`= text(71%) xx 4pi xx 6400^2`
`= 365\ 450\ 163.7…`
`= 3.7 xx 10^8\ text(km²)\ \ text{(nearest km²)}`
The table shows the relative frequency of selecting each of the different coloured jelly beans from packets containing green, yellow, black, red and white jelly beans.
\begin{array} {|c|c|}
\hline
\rule{0pt}{2.5ex} \textit{Colour} \rule[-1ex]{0pt}{0pt} & \textit{Relative frequency} \\
\hline
\rule{0pt}{2.5ex} \text{Green} \rule[-1ex]{0pt}{0pt} & 0.32 \\
\hline
\rule{0pt}{2.5ex} \text{Yellow} \rule[-1ex]{0pt}{0pt} & 0.13 \\
\hline
\rule{0pt}{2.5ex} \text{Black} \rule[-1ex]{0pt}{0pt} & 0.14 \\
\hline
\rule{0pt}{2.5ex} \text{Red} \rule[-1ex]{0pt}{0pt} & \\
\hline
\rule{0pt}{2.5ex} \text{White} \rule[-1ex]{0pt}{0pt} & 0.24 \\
\hline
\end{array}
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--- 2 WORK AREA LINES (style=lined) ---
i. \(\text{Relative frequency of red}\)
\(= 1-(0.32 + 0.13 + 0.14 + 0.24)\)
\(= 1-0.83\)
\(= 0.17\)
ii. \(P\text{(not selecting black)}\)
\(= 1-P\text{(selecting black)}\)
\(= 1-0.14\)
\(= 0.86\)
A family currently pays $320 for some groceries.
Assuming a constant annual inflation rate of 2.9%, calculate how much would be paid for the same groceries in 5 years’ time. (2 marks)
`$369.17\ \ text{(nearest cent)}`
| `FV` | `= PV(1 + r)^n` |
| `= 320(1.029)^5` | |
| `= $369.1703…` | |
| `= $369.17\ \ text{(nearest cent)}` |
Consider the equation `(2x)/3-4 = (5x)/2 + 1`.
Which of the following would be a correct step in solving this equation?
`B`
| `(2x)/3-4` | `= (5x)/2 + 1` |
| `(2x)/3` | `= (5x)/2 + 5` |
`=>B`
The area of the triangle shown is 250 cm².
What is the value of `x`, correct to the nearest whole number?
`D`
`text(Using)\ \ \ A = 1/2ab\ sin\ C`
| `250` | `= 1/2 xx 30x\ sin\ 44^@` |
| `250` | `= 15x\ sin\ 44 ^@` |
| `:.x` | `= 250/(15\ sin\ 44^@)` |
| `= 23.99…\ text(m)` |
`=>D`
What amount must be invested now at 4% per annum, compounded quarterly, so that in five years it will have grown to $60 000?
`C`
`text(Using)\ \ FV = PV(1 + r)^n`
| `r` | `= text(4%)/4` | `= text(1%) = 0.01\ text(per quarter)` |
| `n` | `= 5 xx 4` | `= 20\ text(quarters)` |
| `60\ 000` | `= PV(1 + 0.01)^(20)` |
| `:.PV` | `= (60\ 000)/1.01^(20)` |
| `= $49\ 172.66…` |
`⇒ C`