Q&A - PSLE Math

[tianzhu]

Treelodge:

Hi, can you please explain how did you get 9 units

Hi

Students may use \"Working Backwards\".

Hope this helps.

Best wishes

http://farm9.staticflickr.com/8037/7891838488_550ab4094f_z.jpg\">

[babyj]

lizawa:

Moderator's Note: Please use this thread to ask for help on specific questions. Please refrain from out of topic chatter in this thread to make it easier for the community to find the answers they need.


2 examples of P6 Maths problem sums :

1. David had 2 bags of marbles. After he had sold 44 marbles from Bag X to his friend, the number of marbles in Bag Y was 5/7 of the number of marbles in Bag X. Given that there were 2/5 as many marbles in Bag Y as in Bag X originally, find the number of marbles in Bag X at first.


2. John read a book in 3 days. He read 35% of the total number of pages in the book on the 2nd day. The ratio of the total number of pages of book he read on the 1st and 2nd day to the number of pages he read on the 3rd day was 11:9. If he had read 75 more pages on the 3rd day than on the 1st day, how many pages of the book did he read on the 2nd day ?


Not only must the child be good at Maths, he/she must also be good at English, in terms of interpreting and understanding the question.

These type of questions need to encounter by students frequently to master the techniques. The easiest method is to solve by ratio , after drawing models to , place the fractions in units form, you will understand it better.
Hope it helps.

[kwcllf]

Hi, please help.


2 buses, A and B, travel from the same end of the road at the same time in the same direction. After travelling 6 minutes, Bus A overtakes a cyclist. 2 minutes later, Bus B overtakes the same cyclist. If A and B travel at an average speed of 1000m/min and 800m/min respectively, what is the average speed of the cyclist?

Thanks.

[MathIzzzFun]

kwcllf:

Hi, please help.


2 buses, A and B, travel from the same end of the road at the same time in the same direction. After travelling 6 minutes, Bus A overtakes a cyclist. 2 minutes later, Bus B overtakes the same cyclist. If A and B travel at an average speed of 1000m/min and 800m/min respectively, what is the average speed of the cyclist?

Thanks.

At 6 min from starting (bus A & B),
Distance of cyclist & Bus A from start point = 1000m/min x 6 min= 6000m

At 8 min from starting (bus A & B),
Distance of cyclist & Bus B from start point = 800m/min x 8 min= 6400m

In 2 min,
distance travelled by cyclist = 6400m-6000m = 400m
Cyclist's speed = 400m/2min = 200m/min

cheers.

[kwcllf]

MathIzzzFun:

kwcllf:

Hi, please help.


2 buses, A and B, travel from the same end of the road at the same time in the same direction. After travelling 6 minutes, Bus A overtakes a cyclist. 2 minutes later, Bus B overtakes the same cyclist. If A and B travel at an average speed of 1000m/min and 800m/min respectively, what is the average speed of the cyclist?

Thanks.

At 6 min from starting (bus A & B),
Distance of cyclist & Bus A from start point = 1000m/min x 6 min= 6000m

At 8 min from starting (bus A & B),
Distance of cyclist & Bus B from start point = 800m/min x 8 min= 6400m

In 2 min,
distance travelled by cyclist = 6400m-6000m = 400m
Cyclist's speed = 400m/2min = 200m/min

cheers.

Thanks! you made it look so easy :salute:

[Winx5015]

Hi please help me to solve this question.


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?

Thanks.

[underthesea]

This is dd’s prelim question.


Mrs B used either 4 red buttons or 2 blue buttons to make each dress. The total number of dresses she made was 35. The total number of red buttons used was 74 more than the total number of red buttons used.

(a) how many red buttons were used altogether?
(b) how many blue buttons were used altogether?

Besides guess & check, any other method to solve this problem?

TIA.

[tianzhu]

Winx5015:

Hi please help me to solve this question.


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?

Thanks.

Hi

At first

Red ------ 60%

Green ------- 40%

He lost some of his red beads and the percentage of the beads which were red decreased by 40%.

60% * 60/100 ------- 36%

36 + 40 ------ 76

76% ------- 760

1% -------- 10

36% -------- 360 (number of red beads left)

Number of red beads at first -------- 60% ------- 600

Number or red beads lost ------- 600 – 360 ------- 240

Best wishes

[tianzhu]

underthesea:

This is dd's prelim question.


Mrs B used either 4 red buttons or 2 blue buttons to make each dress. The total number of dresses she made was 35. The total number of red buttons used was 74 more than the total number of red buttons used.

(a) how many red buttons were used altogether?
(b) how many blue buttons were used altogether?

Besides guess & check, any other method to solve this problem?

TIA.

Hi

Please check sentence highlighted in pink.

I think it should be read as

\"The total number of red buttons used was 74 more than the total number of blue buttons used.\"

GC is one possible way.You may also use \"Make a Supposition\"

Here's an earlier solution for a similar type of question, hope this helps.

For your question,the answers are 96 red buttons (24 dresses with red buttons) and 22 blue buttons (11 dresses with blue buttons).

Best wishes

http://farm8.staticflickr.com/7016/6828705773_53738730b6_z.jpg\">

[its888me]

Need help in 2 Questions, Nanyang Prelim 2010, Paper 2:


Q10:

Kingsley planned to cycle from Town P to Town Q. If he were to cycle at 10 km/h, he would reach Town Q at 7.45pm. If he were to cycle at 12 km/h, he would reach Town Q at 7.15pm. What was the distance between Town P and Town Q?

Q17:

TGhere were some blue marbles and white marbles in a bag. If 70 blue marbles were to be removed from the bag, the ratio of the number of blue marbles to the number of white marbles would be 3 : 4. If 112 white marbles were to be removed from the bag instead, the tatio of the number of blue marbles to the number of white marbles would be 8 : 7. When 48 more blue marbles were to be added into the bag, what percentage of all the marbles would be blue marbles?


TIA!