Q&A - PSLE Math

[Flowermonaster]

Further explanation from my DS.

Lee was 32 km away from town x. Since lee catches up with Joe by 32 km every hour, the difference between 128 and the 32 km(lee was 32km away) is the amount of 32km that lee caught up with. 96/32=3. lee only caught up 32km every hour so lee travelled for 3 hours and was still 32km away.
Therefore, Joe travelled 5 hours in total at 64km/hour
Or
Lee travelled 3 hours at 96km/hour plus 32km since he was 32km away

[fightingmom]

Hi,


Can anyone help in the following qns from RGS 2011 SA1 qns 17:

Varsha had some 20-cent and 50-cent coins.
7/8 of the coins were 20-cent coins and the rest were 50-cent coins.
After Varsha had spent $72.50 worth of 50-cent coins and 5/7 of the 20-cent coins, she had 2/7 of the coins left.
Find the total amount of money Varsha left.

Pls show the working . Ans provided was $110.20

TIA

[jarenchuatw]

Mmm, beginning to see some light there...will spend some time to digest the explanation.


Tks once again!

[mrswongtuition]

http://i40.tinypic.com/k2ntlj.jpg\">

[Dazzle]

MathIzzzFun:

Dazzle:

MathIzzzFun,


I don't understand: 'In the end, children : adults --> 7u+ 7: 10u + 10'
Where did the +7 and +10 come about? Please explain. Thanks.

Hi

10 Adults boarded. So, total number of adults in the end will be original number + 10 ie 10u + 10.
10u + 10 = 10 x (1u +1) --> 10 shares, 1 share--> 1u+1
In the end, adults: children --> 10 shares : 7 shares
7 shares --> 7 x (1u+1) = 7u + 7


cheers.

thanks a lot. Now I understand.

[MathIzzzFun]

fightingmom:

Hi,


Can anyone help in the following qns from RGS 2011 SA1 qns 17:

Varsha had some 20-cent and 50-cent coins.
7/8 of the coins were 20-cent coins and the rest were 50-cent coins.
After Varsha had spent $72.50 worth of 50-cent coins and 5/7 of the 20-cent coins, she had 2/7 of the coins left.
Find the total amount of money Varsha left.

Pls show the working . Ans provided was $110.20

TIA

hi

http://i44.tinypic.com/a27hxz.jpg\">

cheers.

[fightingmom]

MathIzzzFun:

fightingmom:

Hi,


Can anyone help in the following qns from RGS 2011 SA1 qns 17:

Varsha had some 20-cent and 50-cent coins.
7/8 of the coins were 20-cent coins and the rest were 50-cent coins.
After Varsha had spent $72.50 worth of 50-cent coins and 5/7 of the 20-cent coins, she had 2/7 of the coins left.
Find the total amount of money Varsha left.

Pls show the working . Ans provided was $110.20

TIA

hi

http://i44.tinypic.com/a27hxz.jpg\">

cheers.

Got it ! :thankyou: MathIzzzFun !

[fightingmom]

Hi,


I got another question on Rates:

Mr Thomas uses two pipes to fill a pool. The first pipe can fill the pool in 6h. The second pipe can fill the pool in 8h. Two hours after both pipes are turned on, Mr Thomas accidentally opens the pipe which can drain the pool completely in 12h. With the 3rd pipe now remained open, what is the total time taken by Mr Thomas to fill the pool completely?

TIA

[MathIzzzFun]

2DMommy:

Please help me with these 2 P6 questions.


1) The average of the 6th and 7th multiples of an unknown number is 39.
The average of the 7th and 8th multiples of the same unknown number is 45. What is the 8th multiple of the unknown number ?

2) Rahim used some pieces of $2 notes to exchange for 20cents and 50cents coins. If he had 3 more 50cents than 20cents coins from the exchange, how many $2 notes did he use ?

Thanks

Hi

Q1...2nd sentence is redundant.
Total --> 2 x 39 = 78
6u + 7u = 13 u --> 78, 1u --> 78/13 = 6
the number is 6.
8th multiple ---> 48

Q2.
For every $4, exchange 5 x 20-cent coins & 6 x 50-cent coins ie 1 more 50 cent than 20 cent.
To get 3 more 50 cent coins --> exchange 3 x $4 = $12
$12 --> 15 x 20-cent coins + 18 x 50-cent coins.

cheers.

[superhappy]

Hi, can someone help me on this question:


1.Ali, Bryan and Chandran had an average of 200 stamps. Ali and Bryan had 100 stamps more than Chandran while Bryan had 20 more stamps than Ali.

:thankyou: