smc-902-10-Ratios

Number, NAP-L3-CA29

A little athletics club is established in a town.

In the first week, 5 girls and 6 boys joined the club.

In the second week, another 4 boys and some more girls joined the club.

The number of girls in the club was now double the number of boys.

How many girls joined the club in the second week?

7	15	17	20

Show Answers Only

`15`

Show Worked Solution

`text(1st week → 6 boys.)`

`text(2nd week → 6 + 4 = 10 boys.)`

`text(Total girls in 2nd week)`

`= 2 xx 10`

`= 20`

`:.\ text(Girls joining in 2nd week)`

`= 20 – 5`

`= 15`

Number, NAP-A3-CA28

A school has 360 students.

The ratio of boys to girls is 4 to 6.

How many boys attend the school?

`90`	`144`	`216`	`240`

Show Answers Only

`144`

Show Worked Solution

`text(One strategy)`

`text(Ratio is 10 parts split 4 : 6)`

`1/10 xx 360 = 36`

`⇒\ text(Ratio can also be expressed:)`

`4 xx 36:`	`6 xx 36`
`144:`	`216`

`:. 144\ text(boys attend the school.)`

Number, NAP-B3-CA31 SA

Jordan has 4 times as many blue pencils as black pencils.

Altogether he has 90 pencils.

How many blue pencils does he have?

Show Answers Only

`72\ text(blue pencils)`

Show Worked Solution

`text(Let)\ \ x = text(be the number of black pencils)`

`x + 4x`	`= 90`
`5x`	`= 90`
`:. x`	`= 90/5`
	`= 18`

`:.\ text(The number of blue pencils)`

`=90 – 18`

`= 72`

Number, NAP-E3-NC05

Muriel made a batch of cookies.

Each cookie had 4 chocolate chips and 3 jelly snakes on it.

Muriel used 39 jelly snakes in the batch of cookies.

How many chocolate chips did she use?

`13`	`26`	`39`	`52`	`78`

Show Answers Only

`52`

Show Worked Solution

`text(Number of cookies made)`

`=39/3`

`=13`

`:.\ text(Chocolate chips used)`

`=13 xx 4`

`=52`

Number, NAP-F3-NC22

A television broadcasting tower is 800 metres high.

A model of the tower is built with a scale of 1 : 4000.

What is the height of the model?

`5\ text(cm)`	`20\ text(cm)`	`200\ text(cm)`	`320\ text(cm)`

Show Answers Only

`20\ text(cm)`

Show Worked Solution

`text(Model height)`	`= 800/4000`
	`= 0.2\ text(m)`
	`= 20\ text(cm)`