Q&A - PSLE Math

[Hifive]

tianzhu:

Hifive:

A group of pupils calculated their average score for a Science Test. They noted that:

if anyone of them scored 13 marks more, their average score would be 90
if anyone of them scored 5 marks less, their average score would be 87

How many pupils were there in the group?

Hi

13 marks more and 5 marks less, this means a gap of 18 marks.

The difference in average mark is 3 (90-87)

18/3 ----- 6
18 marks are distributed among 6 students.

The answer is 6.

Best wishes.

Hi tianzhu

Thanks for your explanation. Have a nice day!

[mumwgals]

Hi ladies and gentlemen, please help me with this question, if possible to do this question without solving using simultaneously method. Thank you very much.


HPPS prelim paper 2 question 17,

There were 1000 students at the parade ground and indoor sport hall. 40% of the 600 students at the parade ground were girls. 60% of the students at the indoor sport hall were girls. After some students in both venues moved from one venue to the other, 30% of the students in the parade ground and 70% of the students at the indoor sport hall were girls. How many students were there in the indoor sports hall after the movement had taken place?

[smileplease]

Please help :


Colin had $80 more than Donovan at first. After Colin spent 75% of his money and Donovan spent 40% of his money, Donovan had $50 more than Colin. How much money did Colin have at first?


thanks.

[tianzhu]

mumwgals:

Hi ladies and gentlemen, please help me with this question, if possible to do this question without solving using simultaneously method. Thank you very much.


HPPS prelim paper 2 question 17,

There were 1000 students at the parade ground and indoor sport hall. 40% of the 600 students at the parade ground were girls. 60% of the students at the indoor sport hall were girls. After some students in both venues moved from one venue to the other, 30% of the students in the parade ground and 70% of the students at the indoor sport hall were girls. How many students were there in the indoor sports hall after the movement had taken place?

Hi

There are two variables in this question, boys and girls.

The units for boys and girls are of different measures, they are of different objects.

We cannot run away from using simultaneous concept.

This question is crafted in such a way that it is pretty neat to use MD to find out the number of students in the end.

The answer is 450.

Best wishes

[tianzhu]

Hi moderator


Please help to delete.

Duplicated post.

Best wishes

[tianzhu]

raghupavithra:

no they put answer is 20 how i get this answer

Hi

From your understanding on percentages,do you think the answer in the WS is correct?

If the question is \"Express 20 cents as a percentage of $1\", then the answer is 20%

Best wishes

[pensiveowl]

Hi… could someone pls help ans this question - thanks


Mr Lim had some red and green beads. 60% of his beads were red and the rest were green. He lost some of his red beads and the percentage of the beads which were red decreased by 40%. He then had 760 red and green beads left. How many red beads did he lose?
(1) 190
(2) 240
(3) 285
(4) 360

[Cheerfuldad]

Hi tianzhu,


Thank you for directing me to

.

tianzhu:

Cheerfuldad:

Hi all,

Please help with the following questions. (Sorry do not know how to draw the pictures)

Q1. Two rectangular tanks A and B measures 40cm by 20cm....

Q2. There are 2 overlapping rectangles A and B. The .....

Thank you.

Hi

Please refer to Vanilla cake's reply on page 429.

Are those the same questions?

Best wishes

http://www.kiasuparents.com/kiasu/forum/viewtopic.php?f=69&t=280&start=4280

[tianzhu]

smileplease:

Colin had $80 more than Donovan at first. After Colin spent 75% of his money and Donovan spent 40% of his money, Donovan had $50 more than Colin. How much money did Colin have at first?

Hi

You may use UM or MD to solve it.

I use 20units instead of 10units for the common bar (Colin and Donovan) because I want to avoid working with decimals.

At first.
Colin -------- 20 units + 80
Colin ------- 20 units

In the end
Colin ------- 5 units + 20
Donovan ------ 12 units

Donovan had $50 more than Colin.
12 units ------ 5 units + 20 + 50
1 unit ------- 10

Colin ------(20*10) + 80 -------280 at first.

Best wishes

[tianzhu]

Cheerfuldad:

Hi tianzhu,

Thank you for directing me to .

Hi

You're welcome.

Best wishes