Q&A - PSLE Math

[MathIzzzFun]

Bunny27:

MathIzzzFun:

[quote=\"Udon\"]Please help with model drawing, thanks in advance.


Q1 When Mrs Lee was 40 years old, her son was twice her daughter 's age. Mrs Lee will be twice her son's age when her daughter is 28 years old. How old was Mrs Lee when her daughter was 20 years old？

here's a similar question ...

http://www.flickr.com/photos/62167097@N02/5679985631/in/photostream

cheers.

Hi,
I need help on this question:

There were a total of 1200 people in Room A and Room B. 20% of the 500 people in Room A were women and 40% of the people in Room B were men. After some women from Room B moved to Room A, the ratio of the number of men to the number of women in Room B became 9:7. How many women were there in Room A in the end?

TIA[/quote]pls check the question.. the answer is a fraction !

cheers.

[MathIzzzFun]

Jolyn:

Dear Guru


I would need you to solve the maths sum :

Question 1
A)The area of a banner is 4/5m2 .It's width is 3/5m.what is it length?

Question 2
B)A wheel takes 1/12min take a complete revolution. How many revolutions will it make in 1/2 min?

Question 3
A skout hikes along on 8-km route.He has to report at a checkpoint after hiking every 3/4km.How many checkpoints must he report at, including the one at the start and the one at the end?(Note:The distance between the last two checkpoints may be less than 3/4km.)

Q1. 4/5 m² ÷ 3/5 m = 1 1/3 m

Q2. Number of revolutions in 1/2 min = 1/2 ÷ 1/12 = 6

Q3. 8 ÷ 3/4 = 10 2/3
2/3 x 3/4 km = 1/2 km
so total of 10 sections 3/4 km + 1 last section of 1/2 km --> 11 sections

or

8 km = 32/4 km = 30/4 km + 2/4 km = 10 x (3/4) km + 1/2 km

total of 10 sections of 3/4 km each and a final section of 1/2 km --> total 11 sections.

Number of check points including start and end point = 11 + 1 = 12

cheers.

[Ling1177]

Hi


please help me with the question. I need explanations to the answer too.

Alfred and Benedict were given some money each, If Alfred spent $45 each week and Benedict spent $90 each week. Alfred would still have $ 840 left when Benedict spent all his money. If Alfred spent $90 each week and Benedict spent $45 each week. Alfred would still have $210 left when Benedict has spent all his money.
a) How much money did Alfred receive?
b) How much money did Benedict receive?

Terry and Alex have some marbles each. When Terry losed 4/9 of his marbles to Alex, the ratio of Terry’s marbles to Alex’s marbles becomes 2:3.
a) What is the ratio of Terry’s mables to Alex’s marbles at first?
b) Terry plays an other games with Alex and loses 35 marbles to Alex and the ration of Terry’s marbles to Alex’s marbles becomes 1:4. Calculate the number of marbles Terry have in the end.

[MathIzzzFun]

Ling1177:

Hi


please help me with the question. I need explanations to the answer too.

Alfred and Benedict were given some money each, If Alfred spent $45 each week and Benedict spent $90 each week. Alfred would still have $ 840 left when Benedict spent all his money. If Alfred spent $90 each week and Benedict spent $45 each week. Alfred would still have $210 left when Benedict has spent all his money.
a) How much money did Alfred receive?
b) How much money did Benedict receive?

the question is not set properly, although the total amount for each is a whole number (Benedict --> $420, Alfred --> $1050), each would have to spend fraction of a cent in order to spend $45 or $90 a week.

Here is similar question, I have shown four possible approaches :

http://i48.tinypic.com/34t2ukm.png\">

http://i47.tinypic.com/350nrxy.png\">

cheers.

[MathIzzzFun]

Ling1177:

Hi


please help me with the question. I need explanations to the answer too.

Terry and Alex have some marbles each. When Terry losed 4/9 of his marbles to Alex, the ratio of Terry's marbles to Alex's marbles becomes 2:3.
a) What is the ratio of Terry's mables to Alex's marbles at first?
b) Terry plays an other games with Alex and loses 35 marbles to Alex and the ration of Terry's marbles to Alex's marbles becomes 1:4. Calculate the number of marbles Terry have in the end.

After Terry lost 4/9 of his marbles to Alex, (Terry had 5/9 of his marbles left)
Ratio of Terry's marbles : Alex's marbles = 2 : 3 --> 10u : 15u

5/9 Terry's marbles --> 10u
4/9 Terry's marbles --> 8u

Before Terry lost the marbles,
Terry's marles --> 10u + 8u = 18u
Alex's marbles --> 15u - 8u = 7u

a) At first, Terry's marbles : Alex's marbles = 18 : 7

At the start of 2nd game, Terry's marbles : Alex's marbles --> 2u : 3u *total 5u)
In the end, Terry's marbles : Alex's marbles --> 1u : 4u (total 5u)

So, Terry lost 1u of marbles to Alex

1u --> 35

Terry had 35 marbles in the end.

cheers.

[Bingu]

:thankyou: Hi thank you for your information.

[Bunny27]

Justintutor:

This question ratio seems to have a problem because you will not get a whole number. This means your answer might be wrong in the end because people cannot be cut into decimals/fractions

Thanks all! The question is wrong
That's why I tried halfway then dk how to do already.

[Justintutor]

Bunny27:

Justintutor:

This question ratio seems to have a problem because you will not get a whole number. This means your answer might be wrong in the end because people cannot be cut into decimals/fractions

Thanks all! The question is wrong
That's why I tried halfway then dk how to do already.

By the way, where did this question come from???School ws/ paper/ or assessment bk???

[ozora]

I need some pointers in this question.

Zara had 70 more dresses than shirts. She sold 3/4 of the dresses and 3/5 of the shirts. She sold 126 more dresses than shirts. How many dresses were there in beginning?
Besides using models or algebra, any other alternative method like using units to get the answer 460.If possible can provide the solution

[speedmaths.012624com]

ozora:

I need some pointers in this question.

Zara had 70 more dresses than shirts. She sold 3/4 of the dresses and 3/5 of the shirts. She sold 126 more dresses than shirts. How many dresses were there in beginning?
Besides using models or algebra, any other alternative method like using units to get the answer 460.If possible can provide the solution

Hi ozora,

One Possible Solution:

Look at the 2 denominators; 4 and 5.
A common multiple of 4 and 5 is 20.

Let Zara have 20 boxes of shirts.
Let Zara have (20 boxes + 70) dresses.

She sold 3/4 of the dresses;
She sold (15 boxes + 52.5) dresses.

She sold 3/5 of the shirts;
She sold 12 boxes of shirts.

She sold 126 more dresses than shirts.

15 boxes + 52.5 → 12 boxes + 126
(Subtract 52.5 from both sides of the equation)
15 boxes + 0 → 12 boxes + 73.5
(Subtract 12 boxes from both sides of the equation)
3 boxes + 0 → 0 box + 73.5
3 boxes → 73.5
1 box → 24.5
20 boxes → 490
490 + 70 → 560 dresses (at first)

Hope this helps.

Cheers


speedmaths.com


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