## Q&A - PSLE Math

### Re: Q&A - PSLE Math

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

(1) James used 4/7 of his screws and 3/5 of his nails to construct a wooden cupboard. In the end, he had an equal number of screws and nails left. Given that James had a total of 145 screws and nails at first, how many nails did he use to construct the wooden cupboard?

(2) At a fun-raising event, 60% of the people were male and the rest were female. 20% of the female left the event in the afternoon. In the evening, after 33 male and 35 female left the event, 75% of the people at the event were male.

(a) What percentage of the people left the event in the afternoon?

(b) How many people were there at the start of the fun raising event?

(1) James used 4/7 of his screws and 3/5 of his nails to construct a wooden cupboard. In the end, he had an equal number of screws and nails left. Given that James had a total of 145 screws and nails at first, how many nails did he use to construct the wooden cupboard?

(2) At a fun-raising event, 60% of the people were male and the rest were female. 20% of the female left the event in the afternoon. In the evening, after 33 male and 35 female left the event, 75% of the people at the event were male.

(a) What percentage of the people left the event in the afternoon?

(b) How many people were there at the start of the fun raising event?

### Re: Q&A - PSLE Math

Science Clubwilburlim wrote:Someone help me for this question please.

The Robotics Club had twice as many pupils as the Science Club. The ratio of the number of girls to the number of boys in the Robotics Club was 4:1. The ratio of the number of girls to the number of boys in the Science Club was 2:3.

(a) Find the ratio of the number of girls in the Robotics Club to the number of girls in the Science Club.

(b) After 38 girls left the Robotics Club to join the Science Club, the ratio of the number of girls to the number of boys in the Science Club became 9:4. How many girls were in the Science Club in the end?

Code: Select all

```
G : B : Total
2 : 3 : 5
```

Code: Select all

```
G : B : Total
4 : 1 : 5
```

In this case we multiply a factor of 2 to Robotic club to make the total twice of Science Club

Below we have all the ratio sharing a common unit 'u', by making the total of robotic club 10u, which is twice of Science Club of 5u.

Code: Select all

```
Robotic Club Science Club
G : B : Total G : B :Total
8 : 2 : 10 2 : 3 : 5
```

b) For the Science Club,

Before increase of girls, G : B => 2 : 3

After increase on girls, G : B => 9 : 4

What is constant here is the number of boys is the same. We'll make the ratio common for the boys

Before increase of girls, G : B => 8 : 12 (Multiple by 4)

After increase of girls, G : B => 27 : 12 (Mulitple by 3)

Increase in girls 27u-8u = 38

19u = 38

u = 2

In the end, the girls in Science Club = 27u = 54 ####

Last edited by Ender on Mon May 23, 2016 9:42 pm, edited 1 time in total.

### Re: Q&A - PSLE Math

SOS mum wrote:Hi all, ps help. Many tks and God Bless:)

(1) James used 4/7 of his screws and 3/5 of his nails to construct a wooden cupboard. In the end, he had an equal number of screws and nails left. Given that James had a total of 145 screws and nails at first, how many nails did he use to construct the wooden cupboard?

Code: Select all

```
Screws Nails
Used : Unuse Used : Unuse
4 : 3 3 : 2
```

Code: Select all

```
Screws (x 2) Nails (x 3)
Used : Unuse Used : Unuse
8 : 6 9 : 6
```

Total Nails = 9u + 6u = 15u

14u+15u = 145

29u = 145

u = 5

Nails used = 9u = 45 ##

### Re: Q&A - PSLE Math

At the start, let the total of male and female = 100uSOS mum wrote:Hi all, ps help. Many tks and God Bless:)

(2) At a fun-raising event, 60% of the people were male and the rest were female. 20% of the female left the event in the afternoon. In the evening, after 33 male and 35 female left the event, 75% of the people at the event were male.

(a) What percentage of the people left the event in the afternoon?

(b) How many people were there at the start of the fun raising event?

Code: Select all

```
Male: Female
60u : 40u
```

a) % of people left = 8u/100u X 100 = 8% ###

b)

Code: Select all

```
Male : Female
60u : 32u
-33 -35
75p : 25p
```

32u - 35 = 25p

96u - 105 = 75p

96u - 105 = 60u -33

36u = 72

u = 2

At the start there are 100u = 200 people ###

### Re: Q&A - PSLE Math

Club--------------G----------Bwilburlim wrote:Someone help me for this question please.

The Robotics Club had twice as many pupils as the Science Club. The ratio of the number of girls to the number of boys in the Robotics Club was 4:1. The ratio of the number of girls to the number of boys in the Science Club was 2:3.

(a) Find the ratio of the number of girls in the Robotics Club to the number of girls in the Science Club.

(b) After 38 girls left the Robotics Club to join the Science Club, the ratio of the number of girls to the number of boys in the Science Club became 9:4. How many girls were in the Science Club in the end?

R-club initial-----

**8u**---------2u (4:1)

S-club initial-----

**2u**---------3u

After rec 38, S--2u+38-----3u

New ratio for S---9----------4

(a)

**Ratio of R-girls : S-girls is 8u : 2u = 4: 1**

(b) (2u+38)/3u -> 9/4

8u + 152 -> 27u

19u -> 152

u->8

**Hence girls in S club in the end is 2(8)+38 = 54**

### Re: Q&A - PSLE Math

Solution with video in the following link:SOS mum wrote:Hi all, ps help. Many tks and God Bless:)

(1) James used 4/7 of his screws and 3/5 of his nails to construct a wooden cupboard. In the end, he had an equal number of screws and nails left. Given that James had a total of 145 screws and nails at first, how many nails did he use to construct the wooden cupboard?

https://www.facebook.com/permalink.php? ... 4939707325

- happy to be mum
- BlueBelt
**Posts:**368**Joined:**Sat Nov 08,**Total Likes:**2

### Re: Q&A - PSLE Math

need help..

A circular wheel of diameter 35cm makes 100 revolutions in 1 minute. Calculate the distance covered by the wheel in half an hour. Express your answer in km.

A circular wheel of diameter 35cm makes 100 revolutions in 1 minute. Calculate the distance covered by the wheel in half an hour. Express your answer in km.

- MathWithModels
- YellowBelt
**Posts:**11**Joined:**Sun Dec 28,

### Re: Q&A - PSLE Math

**Question:**

*A circular wheel of diameter 35cm makes 100 revolutions in 1 minute.*

Calculate the distance covered by the wheel in half an hour. Express your answer in km.

Calculate the distance covered by the wheel in half an hour. Express your answer in km.

**Answer:**

Radius of the wheel: 35 / 2 = 17.5 cm

Circumference of the wheel: 2 x Pi x Radius = 2 x 3.14 x 17.5 cm = 109.9 cm

Distance covered by the wheel in 1 minute = 109.9 x 100 = 10990 cm

Distance covered by the wheel in half an hour = 10990 x 30 = 329700 cm = 3.297 km

Thanks, Ender, for pointing out the mistake. Fixed now.

Last edited by MathWithModels on Wed May 25, 2016 5:26 pm, edited 1 time in total.

### Re: Q&A - PSLE Math

Thank you very much, EnderEnder wrote:At the start, let the total of male and female = 100uSOS mum wrote:Hi all, ps help. Many tks and God Bless:)

(2) At a fun-raising event, 60% of the people were male and the rest were female. 20% of the female left the event in the afternoon. In the evening, after 33 male and 35 female left the event, 75% of the people at the event were male.

(a) What percentage of the people left the event in the afternoon?

(b) How many people were there at the start of the fun raising event?20% of 40u of female left the party = 8uCode: Select all

`Male: Female 60u : 40u`

a) % of people left = 8u/100u X 100 = 8% ###

b)60u - 33 = 75pCode: Select all

`Male : Female 60u : 32u -33 -35 75p : 25p`

32u - 35 = 25p

96u - 105 = 75p

96u - 105 = 60u -33

36u = 72

u = 2

At the start there are 100u = 200 people ###