## Q&A - PSLE Math

### Re: Q&A - PSLE Math

7/9 of M's salary was twice of A's salary. The ratio of A's salary is to S's salary was 14:5. How much was M's salary if 3 of them have a total salary of $3080?

### Re: Q&A - PSLE Math

angel wrote:7/9 of M's salary was twice of A's salary. The ratio of A's salary is to S's salary was 14:5. How much was M's salary if 3 of them have a total salary of $3080?

Suggested answer

Assuming M's salary = 18 unit (9 x 2)

7/9 of M's = 14 units

Therefore, A's salary will be 7units (14 unit/2)

M's : A's

18 : 7 or

36 :

**14**

A's : S's

**14**: 5

Total salary will be,

36 unit + 14 unit + 5 unit

= 55 unit

55 unit = $3080

1 unit = $56

M's salary will be

36 units x $56

= $2016

### Re: Q&A - PSLE Math

10 people boarded a bus at the first stop. At second bus stop, 2/5 of the passengers alighted. At the third bus stop, 2/3 of the passengers alighted and 5 boarded. There were 15 people in the bus when it left the third bus stop. How many passengers are there in the bus when it first started.

- Joy of Learning 111
- BlueBelt
**Posts:**340**Joined:**Wed Aug 19,**Total Likes:**20

### Re: Q&A - PSLE Math

Good and elegant answer, guest2013. I am sure we all appreciate your kindness in taking the trouble to answer.guest2013 wrote:Assuming M's salary = 18 unit (9 x 2)angel wrote:7/9 of M's salary was twice of A's salary. The ratio of A's salary is to S's salary was 14:5. How much was M's salary if 3 of them have a total salary of $3080?

7/9 of M's = 14 units

Therefore, A's salary will be 7units (14 unit/2)

M's : A's

18 : 7 or

36 :14

A's : S's

14: 5

Total salary will be,

36 unit + 14 unit + 5 unit

= 55 unit

55 unit = $3080

1 unit = $56

M's salary will be

36 units x $56

= $2016

My solution is not as elegant as yours, but then my forte is English, not maths

Here's my effort. I think in more algebraic terms:

M + (M x 7/9 x 1/2) + (M x 7/9 x 1/2 x 1/14 x 5) = 3080

M + (M x 7/18) + (M x 35/252) = 3080

252/252M + 98/252M + 35/252M = 3080

385/252M = 3080

M = 3080 x 252/385

M = $2016

### Re: Q&A - PSLE Math

Suggested answer:angel wrote:10 people boarded a bus at the first stop. At second bus stop, 2/5 of the passengers alighted. At the third bus stop, 2/3 of the passengers alighted and 5 boarded. There were 15 people in the bus when it left the third bus stop. How many passengers are there in the bus when it first started.

At first, assuming passengers = 5 units

At 1st stop, 10 passengers boarded.

When left the 1st stop, passengers = 5 units + 10

At 2nd stop, 2/5 passengers alighted.

When left the 2nd stop, passengers will be

(5 units + 10) x 3/5 =

3 units + 6

At 3rd stop, 2/3 passengers alighted & 5 boarded

When left the 3rd stop, passengers will be

(3 units + 6)/3 +5

= 1 unit + 7

1 unit + 7 = 15

1 unit = 8

5 unit x 8 = 40

At first, there are

**40 passengers**in the bus

### Re: Q&A - PSLE Math

Hi, ps help. Many tks and God Bless:)

(1) There were 1250 adults in a train at the start of the journey. 40% of the adults were men. At the next train station, some adults boarded the train and then the number of men became 4/11 of the total number of adults. There were twice as many women as men that boarded the train.

(a) How many women boarded the train.

(B) how many adults were there in the train in the end?

(2) Dinesh had some fiction and non-fiction books. The number of fiction books was 4/9 of the total number of books he had. After he had donated 80 fiction books and 25 non-fiction books, there were 20% as many fiction books as non-fiction books. Find the total number of books Dinesh had at first.

(3) Betty had 25% as many red buttons as blue buttons. For every dress she made, 3/8 of the buttons used were red and the rest were blue. She used up all her red buttons to make the dresses. She had 28 blue buttons left.

(A) how many red buttons did she have at first?

(B) how many dresses did she make?

(1) There were 1250 adults in a train at the start of the journey. 40% of the adults were men. At the next train station, some adults boarded the train and then the number of men became 4/11 of the total number of adults. There were twice as many women as men that boarded the train.

(a) How many women boarded the train.

(B) how many adults were there in the train in the end?

(2) Dinesh had some fiction and non-fiction books. The number of fiction books was 4/9 of the total number of books he had. After he had donated 80 fiction books and 25 non-fiction books, there were 20% as many fiction books as non-fiction books. Find the total number of books Dinesh had at first.

(3) Betty had 25% as many red buttons as blue buttons. For every dress she made, 3/8 of the buttons used were red and the rest were blue. She used up all her red buttons to make the dresses. She had 28 blue buttons left.

(A) how many red buttons did she have at first?

(B) how many dresses did she make?

- alfretztay
- KiasuGrandMaster
**Posts:**1199**Joined:**Sun Sep 12,**Total Likes:**5

### Re: Q&A - PSLE Math

6 and 12 (the second number could be any other multiple of 6);muska wrote:Find two pairs of numbers such that HCF of each pair of numbers is 6

12 and 18 (the second number could be 6 multiply by another prime number besides 2 and 3 which had already been used).

- alfretztay
- KiasuGrandMaster
**Posts:**1199**Joined:**Sun Sep 12,**Total Likes:**5

### Re: Q&A - PSLE Math

Betty had 25% as many red buttons as blue buttons. For every dress she made, 3/8 of the buttons used were red and the rest were blue. She used up all her red buttons to make the dresses. She had 28 blue buttons left. (a) How many red buttons did she have at first? (b) How many dresses did she make?SOS mum wrote:Hi, ps help. Many tks and God Bless:)

(1) There were 1250 adults in a train at the start of the journey. 40% of the adults were men. At the next train station, some adults boarded the train and then the number of men became 4/11 of the total number of adults. There were twice as many women as men that boarded the train.

(a) How many women boarded the train.

(B) how many adults were there in the train in the end?

(a)

At the start :

1250 adults

40% x 1250 = 500 (men)

60% x 1250 = 750 (women)

or

1250 - 500 = 750 (women)

500 + 1u ------- 4p

3500 + 7u ------- 28p

11 - 4 = 7

750 + 2u ------- 7p

3000 + 8u ------- 28p

1u ------- 500

2u ------- 1000

(b)

500 + 500 ------- 4p

1p ------- 1000/4 = 250

11p ------- 250 x 11 = 2750

or

750 + 1000 ------- 7p

1p ------- 1750/7 = 250

11p ------- 250 x 11 = 2750

Ans : (a) 1000 women; (b) 2750 adults.

(2) Dinesh had some fiction and non-fiction books. The number of fiction books was 4/9 of the total number of books he had. After he had donated 80 fiction books and 25 non-fiction books, there were 20% as many fiction books as non-fiction books. Find the total number of books Dinesh had at first.

F : NF

4u : 5u

– 80 : – 25

———– ———-

1p : 5p

1p -> 4u – 80

5p -> 20u – 400

5p -> 5u – 25

15u -> 375

1u -> 25

9u -> 225

Ans : 225 books.

(3) Betty had 25% as many red buttons as blue buttons. For every dress she made, 3/8 of the buttons used were red and the rest were blue. She used up all her red buttons to make the dresses. She had 28 blue buttons left.

(A) how many red buttons did she have at first?

(B) how many dresses did she make?

(a) red -> 1u + 1u + 1u = 3u

blue -> 1u + 1u + 1u + 1u + 1u + 1u + 1u + 1u + 1u + 1u + 1u + 1u = 12u

12u - 5u = 7u

7u -> 28

1u -> 4

3u -> 12

(b)12/3 = 4 or 12/6 = 2

Alternatively,

20/5 = 4 or 20/10 = 2

.Ans : 12 red buttons; (b) 4 or 2 dresses.

### Re: Q&A - PSLE Math

A, B, C and D had 105 apples. A lost 3 apples and D lost 1/2 of what he had. B bought another 6 apples. C's mom gave him enough apples such that his apples are double of what he had at first. In the end, the 4 boys had equal number of apples. How many more apples than D did A have at first?