Q&A - PSLE Math

[tianzhu]

Neat:

Hi!


I need help!

Please assist on the following question:

Four girls each has some money. Kyna has 1/3 of the total amount of money that Lynn, Gigi and Tin Wing have. Lynn has 1/4 of the total amount of money that Kyna, Gigi and Tin Wing have. Gigi has 1/5 of the total amount of money Kyna, Lynn and Tin Wing have. If Tin Wing has $368, how much money do the four girls have altogether?

Thanks

Hi

Good Morning.

Make the total number of units the same. A common multiple is 60.

K:(L+G+TW) ------ 1:3 (4) ------ 15:45 (60)

L:(K+G+TW) ------ 1:4 (5) ------- 12:48 (60)

G:(K+L+TW) ------ 1:5(6) ------- 10:50 (60)

TW ------ 60 – (15+12+10) ------ 23

23 units ------- 368

1 unit ------- 16

Total amount of money ------ 60*16 -------- 960

Best wishes

[tianzhu]

2DMommy:

Please help me with the following questions :

1) 5 friends were playing Wii games on a Fri afternoon from 3 pm to 6 pm. As there were only 4 consoles, they took turns to play. At any time, 3 of them played while the other 2 friends watched. If each of them had the same amount of playing time, how many minutes did each child play that afternoon?

Hi

Good Morning.

From 3 pm to 6 pm ----- 3h ------ 180 minutes

At any time, 3 of them played while the other 2 friends watched.

180*3 ------- 540

540/5 ------ 108

Best wishes

[Studious Alien]

tianzhu:

Winx5015:

http://i45.tinypic.com/kd8r36.jpg\">

Hi

It's difficult to read your image as it's small.

It looks like this question which was discussed earlier.

Best wishes

http://farm7.staticflickr.com/6063/6139917034_a6c214361a_z.jpg\">

Hi tianzhu,
After seeing your diagram, I do not understand the green arrows part. Please assist. :scratchhead:

[jarenchuatw]

PiggyLalala:

jarenchuatw:

Help, pls...


At a prefect investiture, prefects could bring either one or both their parents along. If the ratio of the number of prefects to the number of parents who attended was 7:9 and 1/7 of the prefects brought only 1 parent, what fraction of the prefects did not bring any parents along?

My answer is 2/7

Yup you arevright, the answer is indeed 2/7. How did you get the answer?

[tianzhu]

Studious Alien:

Hi tianzhu,

After seeing your diagram, I do not understand the green arrows part. Please assist. :scratchhead:

Hi

The green arrow shows the rearrangement of the shaded part to form the circumference of a complete circle.

Best wishes

[tianzhu]

2DMommy:

2) An MRT train set off from 1st station with some passengers on board. The ratio of the number of men to that of women was 5:3. At the 2nd station 3/7 of men and some women alighted. Then the ratio of the number of men to that do women became 10:7. At the 3rd station, 70 men and 196 women got on the train and the number of men was the same as the number of women.

a) how many passengers were there on board the train when it set off from the 1st station?
b) how many women alighted at the 2nd station?

Hi

A neat way is to break down the question into smaller parts.

You may work with MD or units. Some form of visual aid does help one to see.

To save some time, I’ll skip the slide and proceed with some pointers.

Consider the 3rd station

Men ------ 10 parts + 70

Women ----- 7 parts + 196

The number of men was the same as the number of women.

Hence, we have 3 parts ------ 126 or 1 part ------- 42

10 parts ------- 420

7 parts ------- 294

At the 2nd station

4 units ------- 420

1 unit ------ 105

3 units ------- 315

Number of men@station 1 ------- 420 + 315 ------- 735

Number of women@station 1 ------- 441

Number of passengers on board the train when it set off from the 1st station ------- 735 + 441 ------ 1176

Number women alighted at the 2nd station ------- 441 - 294 ------147

Best wishes

[tianzhu]

2DMommy:

It was my boy school homework. As the teacher was on MC the last 2 days, we are still unable to solve or check the answer. Will get him to check the question again. Thank you !

Hi

Have you received any update on this question?

Best wishes

[tianzhu]

pixiedust:

Appreciate help with this :


http://i1197.photobucket.com/albums/aa424/pixie_dust8/mq8.jpg\">

(a) Find the area of shaded parts [3 marks]

Hi

I saw a point A in your image.Before attempting the question, I would like to find out if there is any information on A.

Best wishes

[tianzhu]

Shimmer:

Please help need urgent


Luna had 50% more marbles than Rome. When Luna and Rome each gave 14% of their marbles to Sira, the no. of marbles Sira had increase to 70%. In the end, Luna had 88 more than Sira. How marbles Rome had at first ?

Hi

Where is this question from?

Please help to check.

Best wishes

[tianzhu]

2632parent:

Need help on this simply question


1) 75% of the girl and 25% of the boys in a class of 36 pupils wear glasses. 21 pupils in the class do not wear glasses. How many girl in the class wear glasses?

Thank you

Hi

This question touches on simultaneous concept. You may solve it in a pictorial way, using units and parts or letter of the alphabet.

75% of the girl and 25% of the boys in a class of 36 pupils wear glasses.

With glasses

Girls ------ 3G

Boys ------ 1B

Without glasses

Girls ------ 1G

Boys ------ 3B

4G + 4B ------ 36

1G + 1B ------ 9

21 pupils in the class do not wear glasses.

1G + 3B ------ 21

2B ------ 21 – 9 -------12

1B ------ 6

1G ------- 3

Number of girl in the class @wear glasses ------- 3*3 ------ 9

Best wishes