Q&A - PSLE Math

[tianzhu]

raghupavithra:

John had a sum of money. On Monday, he spent 25% of his money. On Tuesday, he spent 1/3​ of his money. On Wednesday, he spent 25% of what he spent on Monday and Tuesday. If he had $39 left, how much did he have at first?



how to do this.pls help me?

Hi

You may use UM or MD.

Draw a bar of 48 units.

Mon ----- 12 units (25% 0f 48))

Tues ----- 16 units (1/3 of 48)

Wed -----7 (25% of 28)

Left ------ 48 -35 ------13 units

13 units ------39

1 unit ------3

48 units ------144

Best wishes

[tianzhu]

Hi VC


Please refer to your PM.

Best wishes

[tianzhu]

raghupavithra:

how solve this Express $1 as a percentage of 25-cents.


400%
25%
20%
4%

Hi

$1 is 4 times of 25 cents.

Percentage ------4/1*100 -------400%

or 100/25*100 -------400%

Best wishes

[Vanilla Cake]

P5G:

My answer for question 10 is 49.16 kg (correct to 2 decimal places).I minus 3 x 15 from the total weight since the bathroom scale shows 5 kg, which I interprete it to mean each reading will be 5 kg more.

The question does not state to round off the answer, so I correct it to 2 decimal places

http://i53.tinypic.com/29dtmki.png\">
72.6x3-15=202.8

B : A
2 : 3

C : B
4 : 5

B : A : C
10 : 15 : 8

202.8/33x8 = 49.163.... kg = 49.16 kg (2 decimal places)
Yes, this should be the correct answer.

[raghupavithra]

how to get 48

[raghupavithra]

how solve this Express $1 as a percentage of 25-cents.


400%
25%
20%
4%

Hi

$1 is 4 times of 25 cents.

Percentage ------4/1100 -------400%

or 100/25100 -------400%

Best wishes


no they put answer is 20 how i get this answer

[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