alfretztay wrote:(6/60) x 75 = 7.5BigDevil wrote:Never do your checking huh?alfretztay wrote: I would solve the above question as follows :

(a)

24 - 6 = 18 (Both took 18 min to pass each other)

(18/60) x 70 = 21 (Dave had travelled 21km in 18min before he passed by Peter)

(b)

6 minutes after they had passed each other, Dave was still 2 km away from Town B.

(6/60) x 70 = 7 (Dave travelled another 7km in the next 6min)

2 + 7 + 21 = 30 (total distance was 30km)

30/(24/60) = 75

Ans : (a) 21km; (b) 75km/h.

This was the answer I got when I assumed that both started their

travel at the same time.

So if Peter traveled from B to A at 75km/h, and he took

18mins to pass Dave, he would have traveled

(18/60) x 75 = 22.5km

But you also said Dave traveled 21km before passing Peter.

22.5 + 21 = 43.5km total distance....which is not the same as the 30km you worked out.

7.5 + 22.5 = 30

I do concur that the question is flawed but when students are faced with it, they have to do their best to solve it, don't they? I too believe that only the one who set the question should, if not will, know it all.

## Q&A - PSLE Math

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

### Re: Q&A - PSLE Math

### Re: Q&A - PSLE Math

(18/60) x 75 = 22.5 (Peter had travelled 22.5km in 18min before he passed by Dave)alfretztay wrote: 24 - 6 = 18 (Both took 18 min to pass each other)

(18/60) x 70 = 21 (Dave had travelled 21km in 18min before he passed by Peter)

A ----- Dave 21km ---------><-----------Peter 22.5km--------- B

21 + 22.5 <> 30km

alfretztay wrote: 2 + 7 + 21 = 30 (total distance was 30km)

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

### Re: Q&A - PSLE Math

I am aware. What is the best solution, if one is required, then? In other words, what should students do if faced with such a question in an examination setting?BigDevil wrote:(18/60) x 75 = 22.5 (Peter had travelled 22.5km in 18min before he passed by Dave)alfretztay wrote: 24 - 6 = 18 (Both took 18 min to pass each other)

(18/60) x 70 = 21 (Dave had travelled 21km in 18min before he passed by Peter)

A ----- Dave 21km ---------><-----------Peter 22.5km--------- B

21 + 22.5 <> 30km

alfretztay wrote: 2 + 7 + 21 = 30 (total distance was 30km)

### Re: Q&A - PSLE Math

For this case, I guess the acceptable answer should be

(a) 3km (b) 30km/h because the numbers add up with

no contradiction (except to the statement "At the same time,...")

If we assume they both started at the same time, then we

will run into total distance being both 30km and 43.5km.

What we need is a linguist to advice if "At the same time,..."

can mean that they didn't start their journey at exactly the same time.

(a) 3km (b) 30km/h because the numbers add up with

no contradiction (except to the statement "At the same time,...")

If we assume they both started at the same time, then we

will run into total distance being both 30km and 43.5km.

What we need is a linguist to advice if "At the same time,..."

can mean that they didn't start their journey at exactly the same time.

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

### Re: Q&A - PSLE Math

i disagree. Also, a quick check will show 'meanwhile, while, concurrently, in the mean while and simultaneously, ...' as acceptable synonyms for 'at the same time.' More importantly, where is this question quoted from? The setter should set the record straight.BigDevil wrote:For this case, I guess the acceptable answer should be

(a) 3km (b) 30km/h because the numbers add up with

no contradiction (except to the statement "At the same time,...")

If we assume they both started at the same time, then we

will run into total distance being both 30km and 43.5km.

What we need is a linguist to advice if "At the same time,..."

can mean that they didn't start their journey at exactly the same time.

### Re: Q&A - PSLE Math

Yes, good to know the source. We wouldn't want this question gets recycled into the school exams.alfretztay wrote:i disagree. Also, a quick check will show 'meanwhile, while, concurrently, in the mean while and simultaneously, ...' as acceptable synonyms for 'at the same time.' More importantly, where is this question quoted from? The setter should set the record straight.BigDevil wrote:For this case, I guess the acceptable answer should be

(a) 3km (b) 30km/h because the numbers add up with

no contradiction (except to the statement "At the same time,...")

If we assume they both started at the same time, then we

will run into total distance being both 30km and 43.5km.

What we need is a linguist to advice if "At the same time,..."

can mean that they didn't start their journey at exactly the same time.

### Re: Q&A - PSLE Math

Hi..ps help the following questions. Many tks and God Bless:)

1) For every 3 stamps Jiahui gave to Ryan, he would always give 1 back to her.

At first, Ryan had 10 stamps more than Jiahui.

Find the difference between the number of stamps they had in the end after Jiahui had given 12 stamps to Ryan.

2) There were 180 girls and 150 boys in the Arts Theatre and 210 girls and 560 boys in the School Hall at first. After some boys and girls moved from the School Hall to the Arts Theatre, there were an equal number of boys and girls in the Arts Theatre and thrice as many boys as girls in the School Hall.

How many boys and how many girls were moved from the School Hall to the Arts Theatre?

1) For every 3 stamps Jiahui gave to Ryan, he would always give 1 back to her.

At first, Ryan had 10 stamps more than Jiahui.

Find the difference between the number of stamps they had in the end after Jiahui had given 12 stamps to Ryan.

2) There were 180 girls and 150 boys in the Arts Theatre and 210 girls and 560 boys in the School Hall at first. After some boys and girls moved from the School Hall to the Arts Theatre, there were an equal number of boys and girls in the Arts Theatre and thrice as many boys as girls in the School Hall.

How many boys and how many girls were moved from the School Hall to the Arts Theatre?

### Re: Q&A - PSLE Math

Sorry, 2 more. Many tks and God Bless:)

1) A farmer had some geese and ducks.

If he bought another 40 ducks, the ratio of the number of ducks to the number of geese would become 5:6.

If he bought another 60 geese instead, then the ratio of the number of ducks to the number of geese would become 2:3.

How many more geese than ducks did the farmer have?

2) Three children, Sally, Lynn and Penny have different amounts of money.

The amount of money Lynn has is the total of Sally and Penny's amount.

The amount of money Penny has is the total of Sally's amount and half of Lynn's amount, Sally has $14.

(a) How much does Lynn have?

(b) How much do these three children have altogether?

1) A farmer had some geese and ducks.

If he bought another 40 ducks, the ratio of the number of ducks to the number of geese would become 5:6.

If he bought another 60 geese instead, then the ratio of the number of ducks to the number of geese would become 2:3.

How many more geese than ducks did the farmer have?

2) Three children, Sally, Lynn and Penny have different amounts of money.

The amount of money Lynn has is the total of Sally and Penny's amount.

The amount of money Penny has is the total of Sally's amount and half of Lynn's amount, Sally has $14.

(a) How much does Lynn have?

(b) How much do these three children have altogether?

### Re: Q&A - PSLE Math

Answer hereSOS mum wrote: 2) There were 180 girls and 150 boys in the Arts Theatre and 210 girls and 560 boys in the School Hall at first. After some boys and girls moved from the School Hall to the Arts Theatre, there were an equal number of boys and girls in the Arts Theatre and thrice as many boys as girls in the School Hall.

How many boys and how many girls were moved from the School Hall to the Arts Theatre?

### Re: Q&A - PSLE Math

Answer hereSOS mum wrote: 1) For every 3 stamps Jiahui gave to Ryan, he would always give 1 back to her.

At first, Ryan had 10 stamps more than Jiahui.

Find the difference between the number of stamps they had in the end after Jiahui had given 12 stamps to Ryan.