Q&A - PSLE Math

[Petkwang]

Belle, Cathy and Denise had a collection of stickers. Cathy and Denise collected 7/10 of the stickers, Belle and Denise collected 6/7 of the stickers, Belle and Cathy collected 620 stickers altogehter. How many more stickers did Denise collected than Belle? Answer 360 stickers


Lily is meeting a friend at a certain time. If she drive 80km/h she will be 1/3 hr late. If she drive at 60km/h, she will be 3/4 hr late. How long will be the journey take if she drive at 90km/h? Answer 1 1/9 hr
Thank you in advance.

[balu_priya]

MathIzzzFun:

balu_priya:

My friend who is too shy to post asked me to help her to post on ksp.

Would appreciate help on the following questions:



2. Father has given Claire and Jane each a certain amount money to spend . If Claire spends $30 each day and Jane spends$20each dayclaire would have $100 left by the time. Jane spends all her money if Claire spends $ 20each day and Jane spends $ 30 each day Claire would have $ 600 left by the time Jane spends all her money . Find the total amount of money given to Claire?

here are 4 approaches to solve such questions -

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cheers.

:thankyou:

[aps]

Hi MathIzzzFun

Thanks for the link!

[balu_priya]

MathIzzzFun:

balu_priya:

My friend who is too shy to post asked me to help her to post on ksp.

Would appreciate help on the following questions:

1.Sam is 5times as old as his sister. iN 10 yrs time Sam will be 12 yrss less than thrice his sisters age then. How much older is Sam than his sister?

Age now,
Sam's sister --> 1 unit
Sam --> 5 units

10 years' time,
Sam's sister --> 1 unit + 10 -- \"thrice\" --> 3 units + 30
Sam --> 5 units + 10

Sam is 12 years less than his sister:
5 units+ 10+12 = 3 units + 30
1 unit --> 4

4 units --> 16

Sam is 16 years older than his sister.

cheers.

:thankyou:

[Michaelia0816]

Tianzhu,

Pls help,

1)Each of the three cards shown below is printed with a different whole number.
The biggest number is 42. When these number are added two at a time, the sums are 57,64 and 77. What are the other 2 numbers?

2) A forty- page newspaper, which consists of only one section, has a sheet with page 9 and page 10 missing. What other pages are missing?

Pls done it by today as I am going to have math prelim the next day~.~

[MathIzzzFun]

Petkwang:

Belle, Cathy and Denise had a collection of stickers. Cathy and Denise collected 7/10 of the stickers, Belle and Denise collected 6/7 of the stickers, Belle and Cathy collected 620 stickers altogehter. How many more stickers did Denise collected than Belle? Answer 360 stickers


Lily is meeting a friend at a certain time. If she drive 80km/h she will be 1/3 hr late. If she drive at 60km/h, she will be 3/4 hr late. How long will be the journey take if she drive at 90km/h? Answer 1 1/9 hr
Thank you in advance.

Q1.
Total -> 70 units
C+D -> 49 units
B --> 70 unit s- 49 units = 21 units

B+D -> 60 units
C --> 70 units – 60 units = 10 units
D --> 60 units – 21 units = 39 units

B --> 21 units, C --> 10 units, D --> 39 units
B+C --> 31 units = 620
1 unit --> 20
39 units – 21 units = 18 units
18 x 20 = 360

Denise collected 360 stickers more than Belle.


Q2.
Ratio of speed at 80 km/h : 60 km/h = 4 : 3
Ratio of time taken to travel same distance at 80 km/h : 60 km/h = 3u : 4u

¾ h – ⅓ h = 5/12 h = 25 min -> travelling at 80km/h is 25 min faster than travelling same distance at 60 km/h

1u -> 25 min, total time taken at 60 km/h
--> 4 x 25 min = 100 min = 2 ⅔ h
Total time taken at 90 km/h = 60/90 x 2 ⅔ h = 10/9 h = 1¹∕₉ h

cheers.

[tianzhu]

Michaelia0816:

Tianzhu,

Pls help,

1)Each of the three cards shown below is printed with a different whole number.
The biggest number is 42. When these number are added two at a time, the sums are 57,64 and 77. What are the other 2 numbers?

Hi

Hope this helps.

Best wishes

http://farm9.staticflickr.com/8440/7836643020_0af55760ca_z.jpg\">

[2DMommy]

Please help me with these :


Find the sum of 35 + 37 + 39 + 41 + 43 … + 231 + 233.

What is the short cut to this question ?

Thank you.

[superksmum]

Hi please help on this question (Henry Park Prelim 2011, question 16).


Mr Lee took 7 hours to travel from Town A to Town B while Mr Wong took 8 hours to travel from Town B to Town A. Both of them did not change their spped throughout the journey. Both of them started off at the same time and moved towards each other. 3 hours later, they were 110km apart. What was the speed Mr Lee was driving?

Thank you.

[whitety]

Hi, need help on this qn.


Every Sat, Mabel will go for her usual exercise. If she runs up 32 steps and walks up 68 steps, she will take 184 seconds. If she runs up 50 steps and walks 50 steps, she will take 175 seconds. If she runs at the same rate throughout the whole exercise, how long will she take to run the 100 steps?


Thanks!