Q&A - PSLE Math

[MathIzzzFun]

ozora:

MathIzzzFun:

[quote=\"ozora\"]need help in this question.

The ratio of Alice's savings to Cat's savings was 1:3.
They shared the cost of a present in the ratio of 2:5.
Alice used 1/3 of her savings while Cat had $57 left after buying the present.
How much was the present?

Hi

could you check the question - should $57 be $52 ?

MD to solve this problem sum...

http://i55.tinypic.com/2ls8tci.jpg\">

cheers.

is $57. the given answer is 266.
why is that 3 units are cut into 18 units?[/quote]Hi

Given answer is incorrect.
If amount spent on present is $266 :
Alice's share = 2/7 x $266 = $76, Alice had $76 x 3 = $228 at first.
Cat's share = 5/7 x $ 266 = $190, Cat had $190 + $57 = $247 at first.

Alice's savings : Cat's savings = 228 : 247, not 1:3

http://i55.tinypic.com/qpjf9x.jpg\">

cheers.

[tianzhu]

Andrew Lee:

Hi, can help me solve this question?
Joamme & tomomi bought the same bag from the same shop when they went shopping together. joanne spent 75% of her money on the bag & tomoni spent 2/3 of hers. What % of their total sum of money was the cost of a bag if the girls had $100 left together? (round off to nearest tenth). Thank :love:

Hi

A quick one, I don’t have the time to draw the MD now.

Since we are talking about the same bag, J and T spend the same amount of money each.

Using “Equal Concept”

Joamme ----- 6 units (spent), 2 units (left)
Tomomi ------6 units (spent), 3 units (left)

5 units ----- 100
1 unit ---- 20

A bag ----- 6*20 ----- 120
Total amount of money ----- 17*20 ----- 340

120/340*100% ------ 35.3%

Hope this helps.

Best wishes

[Dreamerz]

Hi can anyone help me with this question?


Lillian had 600 beads and 35% of them were blue.Meena had 400 beads, 45% of them were blue. After giving some of their beads to each other, 25% of Lillian's beads and 50% of Meena's beads were blue beads.
a) how many beads did Lillian have in the end?
b) how many blue beads did Meena receive from Lillian?

Thank you

[stary]

Hi all,


Have a question here…

440 teachers and pupils participated in a tree planting event. Each teacher planted 2 trees and each group of 4 pupils planted 3 trees. If 455 trees were planted altogether during the event, how many pupils participated in the event?

Many thanks!

[stary]

stary:

Hi all,


Have a question here...

440 teachers and pupils participated in a tree planting event. Each teacher planted 2 trees and each group of 4 pupils planted 3 trees. If 455 trees were planted altogether during the event, how many pupils participated in the event?

Many thanks!

I've used 'Guess and Check' method... Is there any other way?

[tianzhu]

stary:

stary:

Hi all,


Have a question here...

440 teachers and pupils participated in a tree planting event. Each teacher planted 2 trees and each group of 4 pupils planted 3 trees. If 455 trees were planted altogether during the event, how many pupils participated in the event?

Many thanks!

I've used 'Guess and Check' method... Is there any other way?

Hi

You may use a strategy called “Make a Supposition”

There was a similar type of question in this thread.

http://www.kiasuparents.com/kiasu/forum/viewtopic.php?f=27&t=149&start=1160

http://farm6.static.flickr.com/5117/5852149719_2375d991bb_z.jpg\">

For your question,

Assume,or suppose or pretend that all 440 people were teachers.

440*2 ----- 880
(436*2) + 3 ----- 875

880 – 875 ----- 5
For every increase of a group of 4 pupils, the total number of trees drops by 5

880 – 455 ----- 425
425/5 ----- 85.

85*4 -----340

There were 340 pupils.

Have a nice weekend.

Hope this helps.

Best wishes

[tianzhu]

Dreamerz:

Hi can anyone help me with this question?

Lillian had 600 beads and 35% of them were blue.Meena had 400 beads, 45% of them were blue. After giving some of their beads to each other, 25% of Lillian's beads and 50% of Meena's beads were blue beads.
a) how many beads did Lillian have in the end?
b) how many blue beads did Meena receive from Lillian?

Hi

There was a similar type of question in one of the earlier posts.

http://www.kiasuparents.com/kiasu/forum/viewtopic.php?f=27&t=280&start=3060

http://farm6.static.flickr.com/5268/5691587923_36c3de836e_z.jpg\">

A draft solution for your question.

Lillian’s blue beads ----- 35% of 600 ------210
Meena’s blue beads ------ 45% of 400 ----- 180

Total blue beads ----- 390
Total non-blue beads -----(600+400) – 390 ----- 610

1 unit + 1 part ----- 390
3 units + 1 part ---- 610

2 units ----- 220
1 unit ----- 110
1 part ----- 280

a) Lillian ----- 4 units ------- 440
b) 280 – 180 ----- 100

Hope this helps.

Have a great weekend.

Best wishes

[stary]

Thanks tianzhu!

Cheerio!!!

[Belle2011]

At 9am, John was cycling from Point A to Point B. At the same time, Mary was cycling from Point B to Point A using the same route as John. Cycling at a speed of 4km/h faster than Mary, they would pass each other 300m away from the midpoint.

(a) What time did they pass each other?
(b) If John took another 3 minutes to reach Point B, what time would Mary reach Point A?

For (a), I got 4.5 min.
Is this answer correct?

I do not know how to do (b).

Thank-you.

Cheers,
Belle.

[MathIzzzFun]

Belle2011:

At 9am, John was cycling from Point A to Point B. At the same time, Mary was cycling from Point B to Point A using the same route as John. Cycling at a speed of 4km/h faster than Mary, they would pass each other 300m away from the midpoint.

(a) What time did they pass each other?
(b) If John took another 3 minutes to reach Point B, what time would Mary reach Point A?

For (a), I got 4.5 min.
Is this answer correct?

I do not know how to do (b).

Thank-you.

Cheers,
Belle.

Hi

this was discussed in an earlier thread - http://www.kiasuparents.com/kiasu/forum/viewtopic.php?f=27&t=280&start=3470

cheers.