Q&A - P5 Math

[Dragon Flame]

The ratio of the number of stickers Christopher had to the number of stickers Gene had was 1 : 3. After Christopher bought 5 more stickers and Gene bought 9 more stickers, the ratio became 2 : 5. How many more stickers had Gene than Christopher in the end ?

[Dragon Flame]

Alisha bought 12 pencils and 8 erasers. If she had bought these items at 25% discount, the amount of money she saved could buy another 6 more erasers at the usual price. The usual price of a pencil was $1.20. What was the usual price of the eraser ?

Pls help. Thank you very much !

[alfretztay]

The ratio of pupils in the canteen is thrice the number of pupils at the basketball court. 4/9 of the pupils in the canteen are boys. There is an equal number of boys and girls at the basketball court. If there are 125 more boys in the canteen than at the basketball court, how many pupils are there in the canteen ?

… Canteen : Basketball Court

......… 90u : 30u

......… B : G B : G

..... 40u : 50u 15u : 15u

40u – 15u = 25u

25u -> 125

1u -> 5

90u -> 450

Ans : 450 pupils

[alfretztay]

The ratio of the number of stickers Christopher had to the number of stickers Gene had was 1 : 3. After Christopher bought 5 more stickers and Gene bought 9 more stickers, the ratio became 2 : 5. How many more stickers had Gene than Christopher in the end ?

... C : G
... 1u : 3u
... +5 +9
... ----- -----
... 2p 5p

1u + 5 -> 2p
3u + 15 -> 6p
3u + 9 -> 5p

1p -> 6
2p -> 12
5p -> 30
30 - 12 = 18

Ans : 18 more stickers

[alfretztay]

Alisha bought 12 pencils and 8 erasers. If she had bought these items at 25% discount, the amount of money she saved could buy another 6 more erasers at the usual price. The usual price of a pencil was $1.20. What was the usual price of the eraser ?

Pls help. Thank you very much !

Let the the usual price of the eraser be $p.

12 x 1.20 = 14.40

25% of 14.40 = 3.60

3.60 + 0.25(8p) = 6p

4p -> 3.60

1p -> 0.90

Ans : $0.90

[BigDevil]

The ratio of pupils in the canteen is thrice the number of pupils at the basketball court. 4/9 of the pupils in the canteen are boys. There is an equal number of boys and girls at the basketball court. If there are 125 more boys in the canteen than at the basketball court, how many pupils are there in the canteen ?

[bcmum]

In a school hall, chairs were arranged in rows such that there were exactly 15 chairs in each row. For a performance, 7 more chairs were added into the school hall and all the chairs were rearranged. There were now exactly 11 chairs in each row and 9 more rows than before. How many chairs are there in the school hall for the performance?

Pls help. Thank you.

[Suz855]

In a school hall, chairs were arranged in rows such that there were exactly 15 chairs in each row. For a performance, 7 more chairs were added into the school hall and all the chairs were rearranged. There were now exactly 11 chairs in each row and 9 more rows than before. How many chairs are there in the school hall for the performance?

Pls help. Thank you.

9x11=99
99-7=92
15-11=4
92/4=23(rows)
Total chairs-->23x15+7=352

[bcmum]

Why do we need to find the diff of 15-11?

Thks.

[BigDevil]

You get 92 chairs by removing (15 - 11) = 4 chairs from each original row.

92 / 4 = 23 gives you the number of original rows.