Q&A - PSLE Math

[Essential]

Hi Tianzhu, need to trouble u with this question. Jim spent $80 and saved the rest of his allowance . When he increased his expenditure by 13 percent , his savings decreased by 20 percent . Find the ratio of the amount he saved to his allowance at first .

[tianzhu]

Essential:

Hi Tianzhu, need to trouble u with this question. Jim spent $80 and saved the rest of his allowance . When he increased his expenditure by 13 percent , his savings decreased by 20 percent . Find the ratio of the amount he saved to his allowance at first .

Hi

Good Morning.

Amount spent ------ 80

% increase ------- 0.13*80 ------- 10.4

Increase in spending leads to decrease in savings

20% ------- 10.4

100% ------- 52 (savings@first)

Allowance@first ------- savings + spending -------- 52 + 80 ------- 132

ratio of the amount he saved to his allowance at first ------ 52/132 -------- 13/33

Best wishes

[tianzhu]

Shimmer:

Need help !


Thanks in advance !

The average height of 6 pupils was 170cm. The average height of the first 4 pupils was 15cm more than the average height of the remaining 2 pupils, Agnes and Tony.
A) find the average height of the remaining 2 pupils, Agnes and Tony.
B) Agnes was 25cm taller than Tony. Find Agnes's actual height.

Hi

Good Morning.

You may use MD or work using units.

Total height for 6 pupils -------- 170*6 -------- 1020

Average height ------ 1 box or 1 unit

Average height of the first 4 pupils ------- 1 unit + 15

15*4 -------- 60

1020 – 60 ------- 960

960/6 ------- 160 (average height for Agnes and Tony)

Total height for , Agnes and Tony ------- 160*2 ------- 320

320 – 25 ------- 295

295/2 ------- 147.5

147.5 + 25 ------- 172.5 (Agnes's actual height)

Best wishes

[Suz855]

Need help,


The difference between thrice my age 3 years later and thrice my age 3 years ago equals my present age. What is my present age?

Is the answer 6 or 18 or both acceptable. Thanks :oops:

[beanbear]

I need help with this sum. The answer given was 56.


The total number of boys was 100% more than the total number of girls in Class A and Class B. The ratio of the number of boys to the number of girls in Class A was 4:3 and the ratio of the number of boys to the number of girls in Class B was 6:1. If there were 8 more boys in Class A than in Class B, find the number of pupils in Class A.

[pixiedust]

Suz855:

Need help,


The difference between thrice my age 3 years later and thrice my age 3 years ago equals my present age. What is my present age?

Is the answer 6 or 18 or both acceptable. Thanks :oops:

I plucked in the answers to check. Answer is 18.

present age = 18
3 years later, age=18+3=21, thrice age=63
3 years ago, age=18-3=15,thrice age=45
difference=63-45=18 <right>

present age = 6
3 years later, age=6+3=9, thrice age=27
3 years ago, age=6-3=3,thrice age=9
difference=27-9=18 <wrong>

[pixiedust]

beanbear:

I need help with this sum. The answer given was 56.


The total number of boys was 100% more than the total number of girls in Class A and Class B. The ratio of the number of boys to the number of girls in Class A was 4:3 and the ratio of the number of boys to the number of girls in Class B was 6:1. If there were 8 more boys in Class A than in Class B, find the number of pupils in Class A.

Class A, B:G -> 4u:3u
Class B, B:G -> 6p:1p

Total G=3u+1p
Total B=4u+6p

Since \"The total number of boys was 100% more than the total number of girls in Class A and Class B\", Total B = 2*Total G.
Total G*2=6u+2p

Hence,
4u+6p=6u+2p
u=2p

Since \"If there were 8 more boys in Class A than in Class B\",
4u-8=6p
8p-8=6p
p=4
hence u=8

-------------------------------------
check :
p=4,u=8
Class A,Boys=4u=32,Girls=3u=24, total=56.
Class B,Boys=6p=24,Girls=1p=4,total=28
All clues matched.

[Essential]

Good morning Tianzhu, thank you for your quick reply. Thank you very much

[beanbear]

pixiedust:

beanbear:

I need help with this sum. The answer given was 56.


The total number of boys was 100% more than the total number of girls in Class A and Class B. The ratio of the number of boys to the number of girls in Class A was 4:3 and the ratio of the number of boys to the number of girls in Class B was 6:1. If there were 8 more boys in Class A than in Class B, find the number of pupils in Class A.

Class A, B:G -> 4u:3u
Class B, B:G -> 6p:1p

Total G=3u+1p
Total B=4u+6p

Since \"The total number of boys was 100% more than the total number of girls in Class A and Class B\", Total B = 2*Total G.
Total G*2=6u+2p

Hence,
4u+6p=6u+2p
u=2p

Since \"If there were 8 more boys in Class A than in Class B\",
4u-8=6p
8p-8=6p
p=4
hence u=8

-------------------------------------
check :
p=4,u=8
Class A,Boys=4u=32,Girls=3u=24, total=56.
Class B,Boys=6p=24,Girls=1p=4,total=28
All clues matched.

Thanks much pixiedust! Nice to see you here. I'm :imdrowning: with doing all these maths sums with DS!!

[beanbear]

I need help with this one. Ans given for (a) 3:20 and (b) 56.


An equal number of men and women were at a party. The ratio of the number of women who wore watches to the number of men who wore watches was 3:11. The ratio of the number of women to the number of men who did not wear watches was 5:3.
(a) Find the ratio of the number of women who wore watches to the number of women who did not wear watches.
(b) When 7 times as many men as women left the party, the ratio of the number of men to the number of women who remained at the party became 35:38. If 560 men remained at the party, how many men left the party?