Q&A - P5 Math

[sunnydays2]

Hi, I’ve got 2 Math questions.


1. Alan and Dennis had some money. If Alan spends $70 and Dennis spends $35, Alan will have $515 left. If Alan spends $35 and Dennis spends $70, Alan will have $2300 left. How much does each of them have?

2. Mr Lim had some stickers and stamps for his class. The number of stickers was 1/2 the number of stamps. After each pupil in the class had received 3 stickers and 8 stamps from Mr Lim, he had 39 stickers and 2 stamps left. What was the total number of stickers and stamps Mr Lim had at first?

[speedmaths.012624com]

sunnydays2:

Hi, I've got 2 Math questions.


1. Alan and Dennis had some money. If Alan spends $70 and Dennis spends $35, Alan will have $515 left. If Alan spends $35 and Dennis spends $70, Alan will have $2300 left. How much does each of them have?

Hi,

Question 1 looks incomplete.
(Probably needs to add \"when Dennis has spent all his money\".)

Anyway, for such questions, one solution is to look at the ratios rather than the actual numbers.

Look at the example given in Chapter 1 of the Raffles Maths Tricks Volume 1 book (see below):

http://i50.tinypic.com/2m7aoev.jpg\">

Can you use the example given above to solve Question 1?

Cheers

speedmaths.com

-

[tianzhu]

sunnydays2:

2. Mr Lim had some stickers and stamps for his class. The number of stickers was 1/2 the number of stamps. After each pupil in the class had received 3 stickers and 8 stamps from Mr Lim, he had 39 stickers and 2 stamps left. What was the total number of stickers and stamps Mr Lim had at first?

Hi

Hope this helps.

Best wishes

http://farm8.staticflickr.com/7214/6994422784_250a9bcd20_z.jpg\">

[prayhardmum]

Can someone help the following question, please? Thanks.


Three sisters Lisa, Ming and Nora shared the cost of a present to their father. Lisa paid 1/4 of the total share of Ming and Nora. Ming paid 1/9 of the total share of Lisa and Nora. Nora paid $60 more than Ming. How much did the present cost?

[mrswongtuition]

prayhardmum:

Can someone help the following question, please? Thanks.


Three sisters Lisa, Ming and Nora shared the cost of a present to their father. Lisa paid 1/4 of the total share of Ming and Nora. Ming paid 1/9 of the total share of Lisa and Nora. Nora paid $60 more than Ming. How much did the present cost?

L : N : M : Total
1: -- 4 --: 5
-- 9--: 1 : 10

The total amount is the same.
Therefore we need to multiply the first ratio by 2 to make the total number of units the same.

L : N : M : Total
2: -- 8 --: 10
-- 9--: 1 : 10
2 : 7 : 1 : 10

7 - 1 = 6 units
6 u --> $60
1 u --> $10
10 u --> $100

[prayhardmum]

Please also help with this question. Thanks.


Jason and Kevin were given some money each. If Jason and Kevin spent $100 and $50 respectively, Jason would have $1300 when Kevin had spent all his money. If Jason and Kevin spent $50 and $100 each day respectively, Jason would have $3700 when Kevin spent all his money. How much money was given to Jason at the beginning?

[alderbaran]

prayhardmum:

Please also help with this question. Thanks.


Jason and Kevin were given some money each. If Jason and Kevin spent $100 and $50 respectively, Jason would have $1300 when Kevin had spent all his money. If Jason and Kevin spent $50 and $100 each day respectively, Jason would have $3700 when Kevin spent all his money. How much money was given to Jason at the beginning?

Concept: The amount Kevin spent in both scenarios are the same. In the first scenario, Kevin spent 2 units of $50 and Jason spent 2 units of $100. In the second scenario, Kevin spent 1 unit of $100 and Jason spent 1 unit of $50. They are represented in the block diagram below:

......Kevin......................................Jason
[.50u.][.50u.].............[.....100u.....][.....100u.....][..1300..]
[....100u....]..............[.50u.][................3700...............]

Looking at Jason,

Difference in units:
200u - 50u = 3700 - 1300
150u = 2400
u = 16

At the beginning Jason had:
200u + 1300 = 200x16 + 1300 = 4500 (ans)

Sorry for bad diagram (had to use dots to align the blocks)

[sunnydays2]

Thank you!

[zeemimi]

There are some crystal and glass marbles in a pouch. If 3 crystal marbles are removed from the pouch, the number of crystal marbles left will be 1/6 of the glass marbles left. If 5 glass marbles are removed from the pouch, the number of crystal marbles left will be 1/4 of the glass marbles left. How many marbles are there in the pouch at first? ACS paper 2 2011.

[S6169]

Hi, Need some help,

Andy and Betty saved a fixed amount every day. Betty, who started saving earlier, saved $4 each day. By the 10th dayof Betty's savings, Andy had saved $18. By the 16th day of Betty's savings, Andy had saved $54.
(a) Find the ratio of Andy's savings to Betty's savings. (leave your answer in the simplest form)
(b) On which day of Betty's savings will Andy save the same amount as Betty? RGS SA1 2011

Question (b) is ask about on which day of Betty's savings when they saved the same amount of money or how much is the same amount? Confused by the answer sheet. :? Thanks a lot!