Q&A - P3 Math

[MathIzzzFun]

allcc6:

The sugar in the shop was sold in 200-g and 50-g packets. Mrs Tan realised that if she were to buy the 200-g packets, she will buy 15 fewer such packets than if she were to buy the 50-g packets. What was the minimum amount of sugar that Mrs Tan need to buy?


Other than listing method, is there any other method to solve this?

Hi

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or the difference concept:

200g = 4 x 50g --> every 200g packet bought = 3 fewer 50g packets
15/3 = 5 --> 5 x 200 g packets = 1 kg sugar

cheers.

[SAHM Chew]

I started early this yr and there were around 15x pages. I took 3 months to read through most of the questions. Yap, it is the price to pay when we are concerned about our kids.

jass:

@kwcllf thanks for taking the effort to remember to check for me. really appreciate.

@SAHM Chew i swallow saliva when i read your comments. there are 187 pages. *swallowing ... the price to pay as a parent

btw my girl said something today. she dislikes homework and why wouldn't the school consider extending the hours to full day so they could finish all work in class and get questions answered, confusion clarified.

deep down in my heart, i also wonder why sch's so much tougher now.

well, i have to buck up and work on myself in order to help her.

thanks again for your help! gonna get the books tmr. :xedfingers:

[kiasu2008]

Hi,


Can anyone help me on this question.

A + B + B = 10
A x B x B = ▲ = x
What does B stand for ?

[kiasu2008]

Another question :


Mr Tan bought 4 durians and 5 watermelons for $88. Three watermelons cost as much as 2 durians. Find the cost of a durian.

[SAHM Chew]

kiasu2008:

Another question :


Mr Tan bought 4 durians and 5 watermelons for $88. Three watermelons cost as much as 2 durians. Find the cost of a durian.

He bought 4 durians and 5 watermelons

D D D D W W W W W
2Durians cost as much as 3 Watermelons
4D = 6 watermelons
total = 11 watermelons
11 watermelons = $88
1 watermelons = $88/11= $8

2Durians= 3 Watermelons
2 durians = 3x $8
2 durians = $24
1 durian = $12

[kwcllf]

kiasu2008:

Another question :


Mr Tan bought 4 durians and 5 watermelons for $88. Three watermelons cost as much as 2 durians. Find the cost of a durian.

4 durians + 5 Watermelons = $88
2 durians = 3 Watermelons

Substitute the 4 durians with 4/2 x 3 watermelons = 6 watermelons

6 Watermelons + 5 Watermelons = $88
1 Watermelon = $88/11 = $8

Since 2 durians = 3 Watermelons
2 durians = 3 x $8 = $24
Therefore, 1 durian = $24/2 = $12

[ponyo]

[quote]Hi,


Can anyone help me on this question.

A + B + B = 10
A x B x B = ▲ = x
What does B stand for ?[/quote]Ans: B=3
Use guess and check method.We assume A and B are non zeros and A and B are whole numbers ie no decimals. Clearly A, B are from 2-8
So if A=2, B=4, then AXBXB=32 but then this is not a perfect square (ie 1,4,9,16,25 etc) so that rules it out
A cannot be 3, 'cos B will not be a whole no.
Try A=4, then B=3 and AXBXB=4*3*3=36 and which is also a perfect square (6 square).

Hence B=3, ▲=36 and =6

Hope that helps. However, I find it odd to test this to a P3

[bluesclue]

Hi,


Can anyone help me with this question?

Mass of a glass of water =400g. After emptying half the water, the mass =240g.

Question: what is the mass of the empty glass?

Thank you.

[CMF]

bluesclue:

Mass of a glass of water =400g. After emptying half the water, the mass =240g.


Question: what is the mass of the empty glass?

If after emptying half the water, the mass (of the remaining half water + glass) = 240g

Then it means half of the water emptied = 160g (400g - 240g)

Therefore full glass of water (without the glass) : 160g x 2 = 320g

The empty glass itself would be : 400g - 320g = 80g

[bluesclue]

CMF:

bluesclue:

Mass of a glass of water =400g. After emptying half the water, the mass =240g.


Question: what is the mass of the empty glass?

If after emptying half the water, the mass (of the remaining half water + glass) = 240g

Then it means half of the water emptied = 160g (400g - 240g)

Therefore full glass of water (without the glass) : 160g x 2 = 320g

The empty glass itself would be : 400g - 320g = 80g

CMF,
Thanks for your post. The model answer given is 40g. Any thoughts why?