Q&A - PSLE Math

[tianzhu]

smileplease:

Please help with these 3 Qs:


1) John takes part in a race in which he needs to walk, run and cycle. He walks for 1km, runs for the next 2km and cycles for the last 3km of the race. He cycles thrice as fast as he runs and runs thrice as fast as he walks. The total time he takes to complete the 3 activities is 42 minutes more than if he has cycled for the whole journey. How much more time does he take to walk than run?

2) Jason has some cups. 10% of the cups are red. The number of red cups is 20% of the number of the blue cups. The rest of the cups are green. If there are 760 green cups, how many cups are there altogether?

3)The average cost of a few cups was $8. After another cup that cost $32 was added, the average cost became $12. How many cups were there in the end?

Hi

Sorry I am rushing out the solutions because you may need them urgently as your exam is near. Please bear with me if there are errors.

Q1

Time taken for
Walk ----- 9 units
Run ----- 3 units
Cycle ------- 1 unit

9 units + 6 units + 3 units -------- 6 units +42
12 units -----42
1 unit ------3.5

Walk ------ 31.5 mins
Run ------ 21 mins

Difference ------ 10.5 mins

Q2

1 unit ------ red
5 units------blue
4 units -----green

4 units -------760
1 unit -------190

Total number ------10 units -------1900


Q3

12-8 -----4

32-12 ------20

The extra $20 is distributed to the original or existing number of cups.

20/4 -----5

5+1 -------6

Best wishes

[Dreamerz]

Dear Stary

Thank you so much

[smileplease]

tianzhu


you are real fast, thank you.

[Daddy]

Hi tianzhu,


How you get ------2 units (25% left) for below question? Thanks.

from 25% --> fraction is 1/4.. :?


An egg seller had chicken eggs, duck eggs and quail eggs. He had 225 more quail eggs than duck eggs. After he had sold 60% of the chicken eggs, 2/3 of the duck eggs and 3 times as many quail eggs as duck eggs sold, he found that he had 25% of his quail eggs and a total of 205 eggs left. Find the total number of eggs he had first.

Thanks.

[MathIzzzFun]

Tang:

tianzhu:

[quote=\"ck123\"]Hi tianzhu


How to teach the kid hexagonal packing? Any formula or pattern ?

Thanks for your enlightenment.

Hi

You may use 50 cents coins to form the pattern as demonstration. If you pack the coins in hexagonal format, you’ll be able to pack them more densely.

Hope this helps.

Best wishes

http://farm7.static.flickr.com/6176/6146554898_54f4db9088_z.jpg\">

Hi,

Sorry, I tried packing in hexagonal pattern, but only got 35 coins.

7 x 3 = 21
7 x 2 = 14
21 + 14 = 35

So it looks like 36 is the answer (12 x 3).

Someone may like to double-check and confirm what is the correct answer?[/quote]
Hi
http://i55.tinypic.com/148k64j.jpg\">

cheers.

[Cheerfuldad]

Hi vlim,


Do u have the solution for paper 2 - Q5, Q12, Q15b, Q16,Q17b ?I tried to solve but could not, can you help!

Thanks.

Regards

vlim:

HiLenny08,
Below is Rosyth maths paper answers.
Paper 1
1. (3) 2. (4) 3. (3) 4. (1) 5. (4) 6. (2) 7. (3) 8. (4)

9. (1) 10. (2) 11. (2) 12. (2) 13. (2) 14. (1) 15. (1)

16. (1,3,9) 17. (2.83) 18. (0.09, 3/11,0.3,3/8) 19. (264)

20. (South-west) 21.(20) 22.(0740) 23. (9:20)

24. 5th col and 3rd roll box.

26. (thursday) 27. (50) 28.(96+4y) 29.(9.5pie +6)

30. (12)

paper 2

1. (8) 2.(41.58) 3.(46) 4.(160) 5. (16 2/3 %) 6. (267)

7. (550) 8. (27pie +38) 9a. (tue and fri) 9b. thur 9c. 174

10. (19 degree) 11. (35 :51) 12. (450) 13a.(1048)

13b. (61) 14.(40.4%) 15a. (15cm) 15b. (8.25am)

16.(273) 17a. (83.78cm) 17b. (209.44 cm2)

18(9.15 am)

[Publica]

tianzhu:

smileplease:

Please help with these 3 Qs:


1) John takes part in a race in which he needs to walk, run and cycle. He walks for 1km, runs for the next 2km and cycles for the last 3km of the race. He cycles thrice as fast as he runs and runs thrice as fast as he walks. The total time he takes to complete the 3 activities is 42 minutes more than if he has cycled for the whole journey. How much more time does he take to walk than run?

Hi

Sorry I am rushing out the solutions because you may need them urgently as your exam is near. Please bear with me if there are errors.

Q1

Time taken for
Walk ----- 9 units
Run ----- 3 units
Cycle ------- 1 unit

9 units + 6 units + 3 units -------- 6 units +42
12 units -----42
1 unit ------3.5

Walk ------ 31.5 mins
Run ------ 10.5 mins

Difference ------21 mins

Best wishes

Hi Tianzhu,

My son was working on this question and has 10.5 mins as answer. He thinks that the Run should be 21 mins instead, which is 3.5 x 6 units.

Thanks.

[tianzhu]

Daddy:

Hi tianzhu,


How you get ------2 units (25% left) for below question? Thanks.

from 25% --> fraction is 1/4.. :?


An egg seller had chicken eggs, duck eggs and quail eggs. He had 225 more quail eggs than duck eggs. After he had sold 60% of the chicken eggs, 2/3 of the duck eggs and 3 times as many quail eggs as duck eggs sold, he found that he had 25% of his quail eggs and a total of 205 eggs left. Find the total number of eggs he had first.

Thanks.

Hi

You're correct.

25% ------ 25/100 ------ 1/4 ------ 2/8

Best wishes

[tianzhu]

Publica:

Hi Tianzhu,

My son was working on this question and has 10.5 mins as answer. He thinks that the Run should be 21 mins instead, which is 3.5 x 6 units.

Thanks.

Hi

Your boy is correct.

The answer is 10.5.

I'll revise the answer.Thank you for highlighting the error.

Best wishes

[yingxuan0806]

Tanks P and Q are each filled with some water. If water from Tank Q is poured into Tank P until the water in Tank P reaches the brim, there will be 5 litres of water left in Tank Q. If water from Tank P is poured into Tank Q until the water in Tank Q reaches the brim, there will be 17 litres of water left in Tank P. The ratio of volume of Tank P to the volume of Tank Q is 3 : 1. How many more litres of water are needed to fill both tanks to their brim?

can help me solve this question? if yes, can you please use ration n algebra?? preferably dont use model method. ty in advance