Q&A - PSLE Math

[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.

[Dreamerz]

Thank you tianzhu

[tianzhu]

Dreamerz:

Thank you tianzhu

Hi Dreamerz

Good Morning.

You’re welcome.

Best wishes

[tianzhu]

stary:

Thanks tianzhu!

Cheerio!!!

Hi stary

GoodMorning.

You’re welcome.

Best wishes

[Super Alice]

Hope some one can help on the following question:


The cost of 3 mangoes is the same as the cost of 5 gapefruits. The cost of 3 mangoes is also the same as the cost of 10 pears. Find the ratio of the cost of a mango to the cost of a grapefruit to the cost of a pear.


Pls help to show steps to get the ratio. Thanks.

[tianzhu]

Super Alice:

The cost of 3 mangoes is the same as the cost of 5 gapefruits. The cost of 3 mangoes is also the same as the cost of 10 pears. Find the ratio of the cost of a mango to the cost of a grapefruit to the cost of a pear.

Hi

You may use MD.

Use a common multiple of 30 (3,5 and 10).

A mango ---- 10 units
A grapefruit ------ 6 units
A pear ----- 3 units.

The answer is 10:6:3

Best wishes