Q&A - P5 Math

[tianzhu]

sunnydays2:

2. Mabel has $200 more than Ben. Mabel gives 60% of her money to Ben. Ben then gives 1/4 of his money to Mabel. In the end, Ben has $200 more than Mabel. How much did Mabel have at first?

Hi

You may use MD or work using units.

Mabel ------- 5 units + 200
Ben -------- 5 units

After, Mabel gives 60% of her money to Ben.

Mabel ------- 2 units + 80
Ben -------- 8 units + 120

After Ben gives 1/4 of his money to Mabel.

Mabel ------- 4 units + 80 + 30
Ben -------- 6 units + 90

In the end, Ben has $200 more than Mabel.

6 units + 90 ------- 4 units + 80 + 30 + 200
2 units ------- 220
1 unit ------- 110

Mabel @ first -------- (5*110)+ 200 ------750

Best wishes

[tianzhu]

sunnydays2:

3. The ratio of the number of boys to the number of girls in a hall was 3:7. After 64 boys and 64 girls left the hall, the ratio of the number of boys to the number of girls became 2:5. Find the number of pupils in the hall at first.

Hi

Since equal number of boys and girls left the hall, the difference in the number of boys and girls stayed the same.

At first
Boys: Girls ------- 3: 7 (difference ---- 4) -------- 9: 21 (difference ---- 12)

In thye end
Boys: Girls ------- 2 : 5 (difference ---- 3) ------- 8 : 20 (difference ---- 12)

1 unit ------ 64

Number of pupils@first ------- 64*30 -------- 1920

Best wishes

[tianzhu]

sunnydays2:

1. Cherry and Lindy each saved a fixed amount of money everyday. Lindy who started saving earlier, saved $5 each day. When Lindy had saved for 12 days, Cherry had saved $27. When Lindy had saved for 31 days, Cherry had saved $84. How many days had Lindy saved when their total savings was $375?

Hi

First we need to find out Cherry’s savings per day.

Lindy started earlier than Cherry.

84 – 27 ------ 57
57/19 ------- 3

Cherry’s saving -------- 3 per day

At the 31 day, their savings -------- 155 + 84 ------- 239

375 – 239 ------- 136

Their combined savings per day -------- 8

Number of days --------- 136/8 -------- 17

31 + 17 -------- 48 (ans)

Best wishes

[sunnydays2]

Thanks Tianzhu! You are good! Do you teach Math?

[ILOVESCIENCE]

small:

ILOVESCIENCE:

can anyone solve this?


Mike and Vince were selling sunglasses at $12 each and $7 each respectively. Total sales collected by both was $4905. The ratio of the number of sunglasses sold by Mike to those sold by Vince is 5:7. How many sunglasses did Mike sell?

thanks!

Hi.

HTH..

http://i50.tinypic.com/1fe7u8.jpg\">

Hi thanks for the replies! Cheers! :celebrate: :thankyou: :lovesite:

[bndreve]

Hi, I need help with a math question.


Hakim and Suresh had some money in the ratio of 13:8. When they each received $133, Hakim will have 4 times as much money as Suresh. How much did Hakim have at first?

Please help me solve this problem.

[tianzhu]

bndreve:

Hi, I need help with a math question.


Hakim and Suresh had some money in the ratio of 13:8. When they each received $133, Hakim will have 4 times as much money as Suresh. How much did Hakim have at first?

Please help me solve this problem.

Hi

Please check with your source.

I think received should be read as gave away.

hakim@first ------ 273
suresh@first ------ 168

hakim@end ------ 140 (4)
suresh@end ------ 35 (1)

Best wishes

[bndreve]

tianzhu:

bndreve:

Hi, I need help with a math question.


Hakim and Suresh had some money in the ratio of 13:8. When they each received $133, Hakim will have 4 times as much money as Suresh. How much did Hakim have at first?

Please help me solve this problem.

Hi

Please check with your source.

I think received should be read as gave away.

hakim@first ------ 273
suresh@first ------ 168

hakim@end ------ 140 (4)
suresh@end ------ 35 (1)

Best wishes

Thanks. No wonder crack my brain still cannot get the result. I think there is a printing error in the paper. It's from last year SA1 of a primary school.

[happyheart]

Can someone help to explain please. Urgent, Thanks.


Minah bought some dolls at an average price of $34 each. She bought another 2 dolls for $58 each, the average price would be $40. How mNy dolls did she buy altogether? Ans: 6

[speedmaths.012624com]

happyheart:

Can someone help to explain please. Urgent, Thanks.


Minah bought some dolls at an average price of $34 each. She bought another 2 dolls for $58 each, the average price would be $40. How mNy dolls did she buy altogether? Ans: 6

Hi happyheart,

One possible method:

Look at the difference in the prices of the dolls bought and the average price:
Difference between $34 and $40 is $6.
Difference between $40 and $58 is $18.

The ratio of the price differences is $6:$18 or 1:3

The ratio of the number of dolls bought will be the reverse, or 3:1. or 6:2.
Minah bought 6 dolls for $34 each, and she bought 2 dolls for $58 each.

Total number of dolls bought is 6 + 2 = 8.

Hope this helps.

Cheers

speedmaths.com

PS
For parents who are keen to learn more about this method, they can come for our Parents' Workshop on 19 May - look for our thread under Happenings forum.
.