Q&A - PSLE Math

[MathIzzzFun]

Chan09:

need some guidance on this?

a) Jack travelled from City A to City B at an average speed of 60 km/h.
He returned from City B to City A at an average speed of 100 km/h.
What was Jack’s average speed for the whole journey?

tks

Hi
one way is to use the time ratio-
time taken from A to B : B to A = 100 : 60 = 5u : 3u --> total time = 8u
Total distance = 60 x 5u x 2 (or 100 x 3 x 2) = 600u
Average speed for whole journey = 600u/8u = 75 km/h

cheers.

[jewelbox]

Tianzhu, thanks for helping me with the PSLE qns on number patterns.

[tianzhu]

brastilava:

Thank-you so much

Hi

You're welcome.

Best wishes

[tianzhu]

jewelbox:

Tianzhu, thanks for helping me with the PSLE qns on number patterns.

Hi

You're welcome.

Best wishes

[fightingmom]

Hi,


Pls help with the following question:

The primary 4 pupils took part in a survey on their favourite sports.11/20 of the pupils like badminton while 80% of them like swimming. 10% of the pupils do not like bAdminton and swimming. If 180 pupils like both swimming and badminton, how many pupils took part in the survey ?

TIA

[tianzhu]

fightingmom:

Hi,


Pls help with the following question:

The primary 4 pupils took part in a survey on their favourite sports.11/20 of the pupils like badminton while 80% of them like swimming. 10% of the pupils do not like bAdminton and swimming. If 180 pupils like both swimming and badminton, how many pupils took part in the survey ?

TIA

Hi

A similar type of question has been discussed before.

For your question, here’s the answer.

11/20 ------ 55% ------- badminton

80% ------- swimming

100% - 10% ------- 90% -------- pupils who chose any of the two sports.

55% + 80% ------- 135%

135% - 90% ------ 45% -------- pupils who chose both badminton and swimming

45% ------ 180

100% ------- 400

Best wishes

http://farm8.staticflickr.com/7243/6966119100_e47f2d8176_z.jpg\">

[fightingmom]

Hi tianzhu,


:thankyou: for the clear explanation with diagram. My DD got it ! Thank you once again !

[tianzhu]

fightingmom:

Hi tianzhu,


:thankyou: for the clear explanation with diagram. My DD got it ! Thank you once again !

Hi

You're welcome.

Best wishes

[brastilava]

Hi, please help in following question:


At a prize-giving ceremony, prize-winners could invite either one or both of their parents to attend. The ratio of the number of prize-winners to the number of parents who attended was 8:11 and 3/8 of the prize-winners bought only one parent. What fraction of the prize-winners did not have any parents attending the ceremony?

[mrswongtuition]

brastilava:

Hi, please help in following question:


At a prize-giving ceremony, prize-winners could invite either one or both of their parents to attend. The ratio of the number of prize-winners to the number of parents who attended was 8:11 and 3/8 of the prize-winners bought only one parent. What fraction of the prize-winners did not have any parents attending the ceremony?

Prize Winners = 8 units
Parents = 11 units

Out of prize winners (8 units), there are 3 groups:
Brought 1 parent = 3/8 of 8 units = 3 units; 3 units x 1 parent = 3 units of parents
Brought both parents } 8 units - 3 units
Did not bring parents } = 5 units

Now, looking at the parents:
11 units - 3 units = 8 units
8 units of parents belong to those who brought BOTH parents.

Prize Winners (brought both parents & did not bring parents):
Brought both parents: 8 units of parents divide by 2 parents per prize winner = 4 units of prize winners
5 units - 4 units = 1 unit of prize winners did not bring parents

1 out of 8 prize winners did not bring their parents. (Ans: 1/8)