Q&A - PSLE Math

[rajamalar]

hi thank you for your method it is fambous

[cimman]

rajamalar:

hi thank you for your method it is fambous

you're welcome.

[imacsg]

At 9am Jerome left P Town for Y Town which was 540 km away. 2 hours later, Michael left P town for Y Town. He travelled at an average speed of 40 km/h faster than Jerome and overtook him at 3 pm.

a) What was Jerome’s average speed?
b) How far was Jerome from Y town when Michael reached his destination?

Can anyone help the above question? Thanks.

[MathIzzzFun]

imacsg:

At 9am Jerome left P Town for Y Town which was 540 km away. 2 hours later, Michael left P town for Y Town. He travelled at an average speed of 40 km/h faster than Jerome and overtook him at 3 pm.

a) What was Jerome's average speed?
b) How far was Jerome from Y town when Michael reached his destination?

Can anyone help the above question? Thanks.

Michael left Town P at 11 am and overtook Jerome at 3 pm ie 4 h later
40 km/h x 4h = 160 km --> Michael travelled 160km more than Jerome in 4h -- this is the \"catch up\" distance which is the distance travelled by Jerome from 9am to 11 am (2h)
Jerome's speed = 160 km/2 h = 80 km/h

alternatively, we can also use time ratio/speed ratio
When they meet,
time taken by Michael --> 11 am to 3 pm --> 4h
time taken by Jerome --> 9 am to 3pm --> 6h
Speed ratio of Michael : Jerome = 6 : 4 --> 3u : 2u
1u --> 40km/h, Jerome's speed --> 2 x 40 km/h = 80 km/h

with this, I think you can work out part (b)


cheers.

[AJH]

tianzhu:

AJH:

Hi - how did u get 480? I got 460. Thank u.

Hi

This question is crafted in such a way that it’s neat to use MD.

You may also use Units and Parts or letters of the alphabet to show the variables.

What you are seeing now is already the MD.The boxes are labelled with units and parts to enable students using the UP to see better.

The number “480” refers to the number of girls.

Best wishes

:thankyou: for your help. But isn't 30% of students in the parade ground and 70% of students at the indoor sports hall = 180 + 280 = 460?

[AJH]

tianzhu:

AJH:

Hi - nd help with this question:


Mr Lee packed some oranges into big boxes and apples into small boxes. Each big box contained 50 oranges and each small box contained 30 apples. After packing, there were 12 more big boxes than small boxes. Given that there were 1240 fewer apples than oranges, how many oranges were there? ( ans: 2200 )

Thank you.

Hi

You may use MD or work with units.

Draw three boxes (stacked up) to show the number of apples.

12*50 ------ 600

Draw five boxes to show the number of oranges. To make the MD look neater, divide 600/5 to give 120, add a bar showing 120 to each of the box.

5 boxes + 600 ------- 3 boxes + 1240

2 boxes ------- 640

1box ------ 320

Number of apples ------- 2200

Best wishes

:thankyou: I understand now.

[imacsg]

Hi MathIzzzFun,

Thanks for your prompt reply.

I know how to do part B. Thanks alot.

[tianzhu]

AJH:

tianzhu:

But isn't 30% of students in the parade ground and 70% of students at the indoor sports hall = 180 + 280 = 460?

Hi

Good Morning.

The number of boys and girls remains the same before and after the transfer. The total number of 1000 did not change at all.

The number of girls stays the same that is 480 before and after.

In this case

Number of girls in the beginning ------- 480

Number of girls in the end (after the transfer)

Parade square ------- 3 parts ------ 3*55 ------- 165 (30% of 550)

Indoor stadium -------- 7 units ------- 7*45 ------- 315 (70% of 450)

Total number ------ 165 + 315 ------- 480

Best wishes

[tamunawara]

hi can someone help me with this problem from Hendry Park preliminary examination 2012


Susie wants to buy a handbag with her savings. If she increases her savings by 10% she will need $14 more to buy the handbag. if she increases her saving by 45% she will have $7 is excess. what is the cost of her handbag?

[tianzhu]

tamunawara:

hi can someone help me with this problem from Hendry Park preliminary examination 2012


Susie wants to buy a handbag with her savings. If she increases her savings by 10% she will need $14 more to buy the handbag. if she increases her saving by 45% she will have $7 is excess. what is the cost of her handbag?

Hi

It helps to draw a simple diagram.

This question is similar to the Excess and Shortage type of questions

35% ------ 14 + 7 ------ 21

5% ------- 3

10% ------ 6

110% ------ 66

Cost of handbag ------- 64 + 14 ------- 80

or

145% ------- 87

Cost of handbag ------- 87 - 7 ------- 80

Best wishes