Q&A - PSLE Math

[CoffeeCat]

Michaelia0816:

8. Miss Kim borrowed a weighing scale in order to measure the weights of 5 girls. The weighing scale, however, can only measure weights of more than 80 kg. Each girl weights less than 80 kg, so Miss Kim arranged in such a way that two girls be weighted at a time and each girl be weighted together with one of the other 4 girls only once, thus making a total of 10 weighing. The following are the results of the 10 reading in kg:

86, 92,96,100,104,109,110,113,119,127
What are the individual weighs of the 5 girls?

Hi.
Given the nature of the information, one may think of 10 eqn in 5 variables, so first declare 5 variables for the weights of the girls. However its not just any a,b,c,d,e, we also imposed an ordering on them , that is we require a<b<c<d<e.
Now is reasoning ... can we match some of the eqns to the numbers? If we can then we can easily solve for the variables.
So one may realise a + b = 86, d+e = 127, a+c = 92, c+e = 119.
These are the only certainties (because we know a+c < b+ c, hence a+c=92, c+d < c+e, hence c+e = 119)
The other certainty we know is to sum up everything, 4(a+b+c+d+e) = 86 + 92 + ... + 127
As of here I believe you should be able to solve the rest by yourself
Find a+b+c+d+e, then find c , then find a, e , etc

[kiasuaunt]

Nd help with this question:


Doris and Felicia have each planned a list of words they want to learn for a spelling competition. If Doris learnt 40 words per day and Felicia learnt 20 words per day, Doris would have another 70 words left to learn while Felicia would hv completed learning all the spelling words. However, if Doris learnt 20 words per day and Felicia learnt 40 words per day, Doris would have 130 words left to learn while Felicia would have completed learning all the spelling words.

a) How many words did Doris plan to learn?

b) If they were to be rewarded with a sticker for every 10 words learned, how many stickers would they have received altogether?

[tianzhu]

kiasuaunt:

Nd help with this question:


Doris and Felicia have each planned a list of words they want to learn for a spelling competition. If Doris learnt 40 words per day and Felicia learnt 20 words per day, Doris would have another 70 words left to learn while Felicia would hv completed learning all the spelling words. However, if Doris learnt 20 words per day and Felicia learnt 40 words per day, Doris would have 130 words left to learn while Felicia would have completed learning all the spelling words.

a) How many words did Doris plan to learn?

b) If they were to be rewarded with a sticker for every 10 words learned, how many stickers would they have received altogether?

Hi

A similar type of question has been discussed before.

You may follow the same strategy.

Best wishes

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[genevieve08]

Hi Please help me with this question:


Mr. Lee had 36 more guppies than goldfish. He sold 1/4 of the guppies and 1/5 of the goldfish. He found that he had sold 28 more guppies than goldfish. The guppies were sold at $o.55 each and the goldfish at $0.85 each. What was the total amount he received?

Thanks in advance.

[MathIzzzFun]

kyp71:

kyp71:

Please help anyone ?


The figures below is made up of a square, a quadrant and a semicircle. (take pie = 3.14)
(a) Find the perimeter of the shaded parts
(b) Find the difference in the area between the shaded parts.
http://i46.tinypic.com/1zxs7sj.jpg\">

Anyone can help me solve ?

Hi

I think you should be able to find the solution with this

http://i49.tinypic.com/344xv9g.png\">

note that such questions are actually same as \"age\" problems ie same gap/difference.

cheers.

[MathIzzzFun]

genevieve08:

Hi Please help me with this question:


Mr. Lee had 36 more guppies than goldfish. He sold 1/4 of the guppies and 1/5 of the goldfish. He found that he had sold 28 more guppies than goldfish. The guppies were sold at $o.55 each and the goldfish at $0.85 each. What was the total amount he received?

Thanks in advance.

Hi

Goldfish --> 20 units
Guppies --> 20 units + 36
1/5 of Goldfish --> 4 units
1/4 of guppies --> 5 units + 9
5 units + 9 = 4 units + 28
1 unit --> 19
Amount received for goldfish sold --> 76 x $ 0.85 = $ 64.60
Amount received for guppies sold --> 104 x $0.55 = $ 57.20
total received --> $121.80

cheers.

[kiasuaunt]

Thank you,Tianzhu.

[sleepyqueen]

sleepyqueen:

Michaelia0816:

Need help with those following hard question, from practice paper!


1) 10 cooks working for 8 hours each, can prepare a meal for 160 people. How many cooks will be needed to prepare a meal for 220 people if they are required to prepare in 8 hours?

for this i get 14 cooks required. Not sure correct or wrong.

There is an update to your question to \" How many cooks will be needed to prepare a meal for 220 people if they are required to prepare in 5 hours?\"

Hence the answer should be 22.
10 cooks 80 hours to cook for 160 ppl
1 cooks took 160/80 = 2ppl per hour
220/2 = 110 hrs required
110/5 = 22 cooks required for 5 hrs of working each

[genevieve08]

Thank you MathIzzzFun for your help.


Can anyone help me with one more math Question?

Julian had 300 more cards than Faizal . Julian gave 3/5 of his cards to
Faizal . Faizal then gave 1/4 of the total number of what he had then
to Julian . In the end , Faizal had 300 more cards than Julian . How
many cards did Julian have at first.

:thankyou:

[tianzhu]

genevieve08:

Can anyone help me with one more math Question?

Julian had 300 more cards than Faizal . Julian gave 3/5 of his cards to
Faizal . Faizal then gave 1/4 of the total number of what he had then
to Julian . In the end , Faizal had 300 more cards than Julian . How
many cards did Julian have at first.

:thankyou:

Hi

This question has been discussed before.

Hope this helps.

Best wishes

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