Q&A - PSLE Math

[daranic]

Qn appears in today’s Maths paper 2:


Alex and Bob were racing around a 400m track. Alex ran at a speed of 190m/min. Bob ran at a speed 25m/min lesser than Alex. How many complete rounds must Alex run to run 300m more than Bob?

[chrisu]

If can selectively choose weekend to read, then why not 525/30 = 17.5. Thus the least no. of days would become 18 days which is not among the mcq answers. I think the answer should be 26days.

[MathIzzzFun]

ozora:

ganchiong:

Can any one answer this question? It came out in the PSLE. 1)Sally has a book that contains 525 pages.Everyday from Monday to Thursday she reads 15 pages and everyday from Friday to Sunday she reads 30 pages.What is gee least number of days she needs to finish reading the whole book?


Ans. 24 days

May I know how u derive it?.Thanks

Hi

interesting question.. I think the key here is Sally reads everyday and most would be misled to assume that it starts on Monday - which will give 26 days. To arrive at least number of days, start reading on Fri - which will give 24 days.

cheers.

[MathIzzzFun]

chrisu:

If can selectively choose weekend to read, then why not 525/30 = 17.5. Thus the least no. of days would become 18 days which is not among the mcq answers. I think the answer should be 26days.

Hi

the question aims to mislead students to start on Mon which will give the answer as 26 days.. however, if the reading starts on Fri, we will arrive at the least number of days which is 24 days.

cheers.

[MathIzzzFun]

daranic:

Qn appears in today's Maths paper 2:


Alex and Bob were racing around a 400m track. Alex ran at a speed of 190m/min. Bob ran at a speed 25m/min lesser than Alex. How many complete rounds must Alex run to run 300m more than Bob?

Hi

I take it that both Alex and Bob started to run at the same time. To build up a gap of 300m, Alex needs to run for at least 300 m / 25m/min = 12 min ie total distance of 12 min x 190 m/min = 2280m or 2280/400 = 5.7 --> 6 complete rounds needed to be at least 300 m ahead.

cheers.

[chrisu]

Like you said, why not start reading on Friday from the start and only read on weekend. Then it takes only 18 days.

MathIzzzFun:

chrisu:

If can selectively choose weekend to read, then why not 525/30 = 17.5. Thus the least no. of days would become 18 days which is not among the mcq answers. I think the answer should be 26days.

Hi

the question aims to mislead students to start on Mon which will give the answer as 26 days.. however, if the reading starts on Fri, we will arrive at the least number of days which is 24 days.

cheers.

[Maths Isnt Fun]

MathIzzzFun:

daranic:

Qn appears in today's Maths paper 2:


Alex and Bob were racing around a 400m track. Alex ran at a speed of 190m/min. Bob ran at a speed 25m/min lesser than Alex. How many complete rounds must Alex run to run 300m more than Bob?

Hi

I take it that both Alex and Bob started to run at the same time. To build up a gap of 300m, Alex needs to run for at least 300 m / 25m/min = 12 min ie total distance of 12 min x 190 m/min = 2280m or 2280/400 = 5.7 --> 6 complete rounds needed to be at least 300 m ahead.

cheers.

Hey today i took the maths psle and i guess it was like average? Well, for this question i put 5 because they said complete rounds so if its 5.7, the max number of complete rounds is only 5.

[Maths Isnt Fun]

chrisu:

Like you said, why not start reading on Friday from the start and only read on weekend. Then it takes only 18 days.

MathIzzzFun:

[quote=\"chrisu\"]If can selectively choose weekend to read, then why not 525/30 = 17.5. Thus the least no. of days would become 18 days which is not among the mcq answers. I think the answer should be 26days.

Hi

the question aims to mislead students to start on Mon which will give the answer as 26 days.. however, if the reading starts on Fri, we will arrive at the least number of days which is 24 days.

cheers.

[/quote]
Yea i guess its meant to mislead but if it is, the setters might as well add an 18 to one of the options. I wasnt rlly sure abt my ans for this question but i put 26 days

[Maths Isnt Fun]

For the last and second last question of maths PSLE does anyone rmb the question? I only remembered my answers but not the questions… =="

[Maths Isnt Fun]

Who noes how to do the question in paper two abt the tiles? For part a my ans was 5/9 and for part b my ans was 180m2. Also, the question before that was abt the chairs. It was something like this…: Someone arranged chairs in a hall and each row had exactly 9 chairs. He then bought 6 chairs and changed the number of chairs in each row to 7.He had 12 extra rows in the end. How many chairs did he have in the hall? I was stuck at this for awhile but i worked it out and my ans was 351