Q&A - PSLE Math

[Cecilia J]

lizawa:

Moderator's Note: Please use this thread to ask for help on specific questions. Please refrain from out of topic chatter in this thread to make it easier for the community to find the answers they need.

xamples of P6 Maths problem sums :

1. David had 2 bags of marbles. After he had sold 44 marbles from Bag X to his friend, the number of marbles in Bag Y was 5/7 of the number of marbles in Bag X. Given that there were 2/5 as many marbles in Bag Y as in Bag X originally, find the number of marbles in Bag X at first.


2. John read a book in 3 days. He read 35% of the total number of pages in the book on the 2nd day. The ratio of the total number of pages of book he read on the 1st and 2nd day to the number of was 11:9. If he had read 75 more pages on the 3rd day than on the 1st day, how many pages of the book did he read on the 2nd day ?

k
Not only must the child be good at Maths, he/she must also be good at English, in terms of interpreting and understanding the question.

3. Mr Tan travelled from Town A to Town B at 1100hrs. When he was 30 km fom Town A , Mr Bala left Town B to Town A at a speed of 18km/h faster than Mr Tan. When Mr Bala reached Town A at 1pm, Mr Tan had completed 90 percent of his journey. What was Mr Tan's average speed?

[Jolyn]

Can someone help on this question please…

[ozora]

need some guide for the following question.

40% of the beads in a box are red and the rest are blue. after some red beads are taken out, the % of the red beads decreased by 10%. then 36 more blue beads were added into the box. in the end they were twice as many blue than red beads. How many blue beads were there at first?

[MathIzzzFun]

ozora:

need some guide for the following question.

40% of the beads in a box are red and the rest are blue. after some red beads are taken out, the % of the red beads decreased by 10%. then 36 more blue beads were added into the box. in the end they were twice as many blue than red beads. How many blue beads were there at first?

at first, red beads : blue beads --> 40u : 60u
red beads reduced by 10%, red beads : blue beads --> 36u : 60u
36 more blue beads added, red beads : blue beads --> 36u : 60u + 36 = 1 : 2

cross multiply/equalize:
72u = 60u + 36
1u --> 3

Blue beads, at first --> 60 x 3 = 180

cheers.

[ozora]

MathIzzzFun:

ozora:

need some guide for the following question.

40% of the beads in a box are red and the rest are blue. after some red beads are taken out, the % of the red beads decreased by 10%. then 36 more blue beads were added into the box. in the end they were twice as many blue than red beads. How many blue beads were there at first?

at first, red beads : blue beads --> 40u : 60u
red beads reduced by 10%, red beads : blue beads --> 36u : 60u
36 more blue beads added, red beads : blue beads --> 36u : 60u + 36 = 1 : 2

cross multiply/equalize:
72u = 60u + 36
1u --> 3

Blue beads, at first --> 60 x 3 = 180

cheers.

Thanks think my equalization went wrong. Thanks for the guide.

[MathIzzzFun]

Cecilia J:

lizawa:

Moderator's Note: Please use this thread to ask for help on specific questions. Please refrain from out of topic chatter in this thread to make it easier for the community to find the answers they need.

xamples of P6 Maths problem sums :

1. David had 2 bags of marbles. After he had sold 44 marbles from Bag X to his friend, the number of marbles in Bag Y was 5/7 of the number of marbles in Bag X. Given that there were 2/5 as many marbles in Bag Y as in Bag X originally, find the number of marbles in Bag X at first.


2. John read a book in 3 days. He read 35% of the total number of pages in the book on the 2nd day. The ratio of the total number of pages of book he read on the 1st and 2nd day to the number of was 11:9. If he had read 75 more pages on the 3rd day than on the 1st day, how many pages of the book did he read on the 2nd day ?

k
Not only must the child be good at Maths, he/she must also be good at English, in terms of interpreting and understanding the question.

3. Mr Tan travelled from Town A to Town B at 1100hrs. When he was 30 km fom Town A , Mr Bala left Town B to Town A at a speed of 18km/h faster than Mr Tan. When Mr Bala reached Town A at 1pm, Mr Tan had completed 90 percent of his journey. What was Mr Tan's average speed?

where is this question taken from ?

http://i40.tinypic.com/ztj18k.png\">

note: there is an error in the working .. for this question, there is no solution - ie there exist no speed for the Mr Tan at which the stated conditions can be met.

In order to get a real value for MR Tan's speed and Bala's speed, the question should be amended as follows:

Mr Tan travelled from Town A to Town B at 11:00. When he was 18 km from Town A , Mr Bala left Town B to Town A at a speed of 18km/h faster than Mr Tan. When Mr Bala reached Town A at 13:00, Mr Tan had completed 90 percent of his journey. What was Mr Tan's average speed?

in this case,
Mr Tan's speed --> 54 km/h and
Bala's speed --> 72 km/h

my apologies for the error.

cheers.

[Easy-going]

Please help with this question

Singapore Chinese Girls' SA 1 2012
Qn 16
Ivy bought some marbles and gave half of them to Joan. Joan bought some stamps and gave half of them to Ivy. Ivy gave away 8 stamps and Joan gave away 12 marbles. The ratio of the number of stamps to the number of marbles Ivy had left then became 1:5 and the ratio of the number of stamps to the number of marbles Joan had left became 1:3. How many stamps did Joan buy?
:thankyou:

[MathIzzzFun]

Easy-going:

Please help with this question

Singapore Chinese Girls' SA 1 2012
Qn 16
Ivy bought some marbles and gave half of them to Joan. Joan bought some stamps and gave half of them to Ivy. Ivy gave away 8 stamps and Joan gave away 12 marbles. The ratio of the number of stamps to the number of marbles Ivy had left then became 1:5 and the ratio of the number of stamps to the number of marbles Joan had left became 1:3. How many stamps did Joan buy?
:thankyou:

similar question here - http://www.flickr.com/photos/mathizzzfun/6943541872/in/set-72157632928079102

cheers.

[lee tong fong]

Hi, can anyone help me in this question


1)The number of chickens in farm A and Farm B are in the ratio 9:1.
Farm A sold a certain number of chickens and Farm B sold 2/3 of its chickens.
As a result, both Farm A and Farm B each had 209 chickens left.

(a) How many chickens were sold by the 2 Farm in all?
(b) What percentage of farm A’s chickens wre sold?

Thanks you

[lee tong fong]

Hi, can anyone help me with another question


(2) Joey has some red and blue beads.
If she buys another 15 red beads, the percentage of the red beads she has become 30%.
If she gives away 20 blue beads, the percentage of the blue beads she has becomes 76%.
However many red beads and blue beads do Joey have?

Thanks you again