## Q&A - PSLE Math

### Re: Q&A - PSLE Math

A painter was standing on the middle rung of a ladder to paint the external wall of a building. He moved up 5 rungs from there to paint the upper section of the wall. From there, he moved down 7 rungs to get a pole lying against the wall. Then he moved up another 6 rungs and remained there to clean up some dirt on the wall. He finally reached the top of the ladder when he went up to 5 more rungs to paint the uppermost section of the wall. How many rungs are there on the ladder?

### Re: Q&A - PSLE Math

A boatman is trying to get upstream 13km. He paddles for 2 hours and rests for 1 hour. He manages to get upstream 3km in every hour that he paddles but each time he rests, the current will bring him backwards 1km. How many hours will he take to reach his destination? TIA

### Re: Q&A - PSLE Math

Hi, I have a query:

The temperature of a cup of hot coffee was 70°C at 11.58a.m. Its temperature dropped by 3.5°C per minute. Its final temperature was 60% lower than the original temperature. At what time was the temperature 60% lower than the original temperature?

Answer provided by assessment book:

60% of 70°C = 60/100 x 70 = 42°C

Difference -> 70 – 42 = 28°C

3.5°C -> 1 min

28°C -> 8 min

11.58a.m. -> 12. 06p.m.

The temperature was 60% lower than the original temperature at 12.06p.m.

How do you interpret 60% lower than the original temperature?

Should the final temperature be 40% of 70°C = 28°C

or 60% of 70°C = 42°C ?

TIA.

The temperature of a cup of hot coffee was 70°C at 11.58a.m. Its temperature dropped by 3.5°C per minute. Its final temperature was 60% lower than the original temperature. At what time was the temperature 60% lower than the original temperature?

Answer provided by assessment book:

60% of 70°C = 60/100 x 70 = 42°C

Difference -> 70 – 42 = 28°C

3.5°C -> 1 min

28°C -> 8 min

11.58a.m. -> 12. 06p.m.

The temperature was 60% lower than the original temperature at 12.06p.m.

How do you interpret 60% lower than the original temperature?

Should the final temperature be 40% of 70°C = 28°C

or 60% of 70°C = 42°C ?

TIA.

### Re: Q&A - PSLE Math

M+5-7+6+6+5=15SOS mum wrote:A painter was standing on the middle rung of a ladder to paint the external wall of a building. He moved up 5 rungs from there to paint the upper section of the wall. From there, he moved down 7 rungs to get a pole lying against the wall. Then he moved up another 6 rungs and remained there to clean up some dirt on the wall. He finally reached the top of the ladder when he went up to 5 more rungs to paint the uppermost section of the wall. How many rungs are there on the ladder?

15+15+1 =

**31**

### Re: Q&A - PSLE Math

Hi,Er Jie wrote:Hi, I have a query:

The temperature of a cup of hot coffee was 70°C at 11.58a.m. Its temperature dropped by 3.5°C per minute. Its final temperature was 60% lower than the original temperature. At what time was the temperature 60% lower than the original temperature?

Answer provided by assessment book:

60% of 70°C = 60/100 x 70 = 42°C

Difference -> 70 – 42 = 28°C

3.5°C -> 1 min

28°C -> 8 min

11.58a.m. -> 12. 06p.m.

The temperature was 60% lower than the original temperature at 12.06p.m.

How do you interpret 60%lower thanthe original temperature?

Should the final temperature be 40% of 70°C = 28°C

or 60% of 70°C = 42°C ?

TIA.

You might want to take a look at this post from CIMMAN,

http://www.kiasuparents.com/kiasu/forum ... 2#p1000542

Regards

### Re: Q&A - PSLE Math

2 hrs -> 6 kmSOS mum wrote:A boatman is trying to get upstream 13km. He paddles for 2 hours and rests for 1 hour. He manages to get upstream 3km in every hour that he paddles but each time he rests, the current will bring him backwards 1km. How many hours will he take to reach his destination? TIA

1 hr rest -> 5km

2 hrs -> 5+6 = 11km

1 hr rest -> 10km

1 hr -> 13km

total ->

**7 hours**

SOS Mum, may I know the source of these questions?

### Re: Q&A - PSLE Math

Sorry, wld u mind explain why is there a need to add additional 6 n how do u derive 15? Many thkssushi88 wrote:M+5-7+6+6+5=15SOS mum wrote:A painter was standing on the middle rung of a ladder to paint the external wall of a building. He moved up 5 rungs from there to paint the upper section of the wall. From there, he moved down 7 rungs to get a pole lying against the wall. Then he moved up another 6 rungs and remained there to clean up some dirt on the wall. He finally reached the top of the ladder when he went up to 5 more rungs to paint the uppermost section of the wall. How many rungs are there on the ladder?

15+15+1 =31

### Re: Q&A - PSLE Math

The highlighted part says that.SOS mum wrote:Sorry, wld u mind explain why is there a need to add additional 6 n how do u derive 15? Many thkssushi88 wrote:M+5-7+6+6+5=15SOS mum wrote:A painter was standing on the middle rung of a ladder to paint the external wall of a building. He moved up 5 rungs from there to paint the upper section of the wall. From there, he moved down 7 rungs to get a pole lying against the wall. Then he moved up another 6 rungs and remained there to clean up some dirt on the wall. He finally reached the top of the ladder whenhe went up to 5 more rungsto paint the uppermost section of the wall. How many rungs are there on the ladder?

15+15+1 =31

Is the answer correct?

### Re: Q&A - PSLE Math

Need some help at the pattern.

458. 459. 925

568. 561. 123

220. 226 677

154. 158. 871

631. _____ 109

What the missing number?

Thanks

458. 459. 925

568. 561. 123

220. 226 677

154. 158. 871

631. _____ 109

What the missing number?

Thanks

### Re: Q&A - PSLE Math

ozora wrote:Need some help at the pattern.

458. 459. 925

568. 561. 123

220. 226 677

154. 158. 871

631. _____ 109

What the missing number?

Thanks

The missing number is

**631**, correct?