Aussie Maths & Science Teachers: Save your time with SmarterEd
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 |
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`15`
`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`
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` |
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`144`
`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.)`
Shelly and Carly collect dolls.
The ratio of the number of dolls Shelly owns compared to Carly is 3 : 2.
Shelley owns 12 dolls.
How many dolls does Carly own?
| `2` | `6` | `8` | `18` |
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`8`
`text(Ratio 3 : 2)`
`text(Let)\ \ x=\ text(Number of Carly’s dolls)`
| `x/12` | `= 2/3` |
| `x` | `= (2 xx 12)/3` |
| `= 8\ text(dolls)` |
Jordan has 4 times as many blue pencils as black pencils.
Altogether he has 90 pencils.
How many blue pencils does he have?
`72\ text(blue pencils)`
`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`
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)` |
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`20\ text(cm)`
| `text(Model height)` | `= 800/4000` |
| `= 0.2\ text(m)` | |
| `= 20\ text(cm)` |