Q&A - PSLE Math

[MathIzzzFun]

Chan09:

Why would you divide by 2?

distance covered by express train --> (1800 + 1200) / 2 = 1500 km

Hi

Draw a simple model,
Bigger block--> expres train
Smaller block --> cargo train
Sum = 1800
Difference = 1200

cheers.

[Neat]

Hi


Tap A can fill a tank completely in 6 minutes. Tap B can fill the same tank completely in 3 minutes. At the beginning, Tap A was turned on to fill the tank. After 1 minute, Tap B was then turned on to fill the tank. How long would it take to fill the tank completely?

Thanks for the time.

[Edureach]

Neat:

Hi


Tap A can fill a tank completely in 6 minutes. Tap B can fill the same tank completely in 3 minutes. At the beginning, Tap A was turned on to fill the tank. After 1 minute, Tap B was then turned on to fill the tank. How long would it take to fill the tank completely?

Thanks for the time.

Let the volume of the tank be in 6 units.

Speed of tap A to fill 1 unit = 1min/6mins for 6 units.
Speed of tap B to fill 1 unit = 30 secs/3mins for 6 units.

Tap A was turned on during 1st min = 1 unit filled.
Tap A & B were turned on during next min = 1+2 units filled.
Time taken to filled 4 units = 2 mins Ans(A).
Balance 2 units to be filled by tap A and B.

It took 60 secs to fill 3 units.
For 2 units time taken = 60 x 2/3 = 40 secs Ans (B).

Total time taken to fill completely = Ans A +B = 2 mins 40 secs.

[superksmum]

Hi, help needed for these questions from Catholic High SA 2011


Ques 16) Jerry bought four times as many pencils as notebooks and spent a total of $21.60. He spent $2.40 more on the notebooks than the pencils. Given that a notebook costs $3.20 more than a pencil, find the cost of a pencil.

Ques 18) at first, Ravi had $200 more than Vincent. He gave 40% of his money to Vincent. Vincent then gave 25% of his money to Ravi. In the end, Vincent had $68 more than Ravi. How much did Vincent give Ravi?


Thank you.

[superksmum]

ACS SA Paper 2011.


Ques 14) Mrs Lee has 60 pencils to give to her class. If she gives each boy 2 pencils and each girl 3 pencils, she will have 6 pencils left over. However, if she gives each boy 3 pencils and each girls 2 pencils, she will have 4 pencils left over. How many pupils are there in Mrs Lee’s class?

Ques: 17) Daphne had 20% fewer books than Jocelyn. Yan Ming had 8 more books than Jocelyn. If Jocelyn were to give 4 books to Daphne, they would both have an equal number of books.

b) Yan Ming went to buy some new books. The ratio of books that Yan Ming had to the ratio that Jocelyn had then become 3:2. How many new books did Yan Ming buy?

Thank you.

[speedmaths.012624com]

superksmum:

Hi, help needed for these questions from Catholic High SA 2011


Ques 18) at first, Ravi had $200 more than Vincent. He gave 40% of his money to Vincent. Vincent then gave 25% of his money to Ravi. In the end, Vincent had $68 more than Ravi. How much did Vincent give Ravi?


Thank you.

Hi,

For Q18, please see pg 604.

http://www.kiasuparents.com/kiasu/forum/viewtopic.php?f=69&t=280&start=6030

cheers

speedmaths.com

.

[superksmum]

speedmaths.com:

superksmum:

Hi, help needed for these questions from Catholic High SA 2011


Ques 18) at first, Ravi had $200 more than Vincent. He gave 40% of his money to Vincent. Vincent then gave 25% of his money to Ravi. In the end, Vincent had $68 more than Ravi. How much did Vincent give Ravi?


Thank you.

Hi,

For Q18, please see pg 604.

http://www.kiasuparents.com/kiasu/forum/viewtopic.php?f=69&t=280&start=6030

cheers

speedmaths.com

.

Hi speedmaths,

Thank you for the diverting.

[MathIzzzFun]

superksmum:

ACS SA Paper 2011.


Ques 14) Mrs Lee has 60 pencils to give to her class. If she gives each boy 2 pencils and each girl 3 pencils, she will have 6 pencils left over. However, if she gives each boy 3 pencils and each girls 2 pencils, she will have 4 pencils left over. How many pupils are there in Mrs Lee's class?


Thank you.

Hi

Q14.
Scenario 1 (2 pencils/boy + 3 pencils/girl)
--> Total pencils given out = 60 - 6 = 54
Scenario 2 (3 pencils/boy+2 pencils/girl)
--> Total pencils given out = 60 - 4= 56

Combined the two scenarios
we have
each boys gets 5 pencils & each girl gets 5 pencils ie EVERYONE gets 5 pencils,
total number given out = 54 + 56 = 110
so, total number of pupils --> 110 / 5 = 22

cheers.

[MathIzzzFun]

superksmum:

ACS SA Paper 2011.


Ques: 17) Daphne had 20% fewer books than Jocelyn. Yan Ming had 8 more books than Jocelyn. If Jocelyn were to give 4 books to Daphne, they would both have an equal number of books.

b) Yan Ming went to buy some new books. The ratio of books that Yan Ming had to the ratio that Jocelyn had then become 3:2. How many new books did Yan Ming buy?

Thank you.

Hi

Q17.
If Jocelyn gives 4 books to Daphne, they will have equal number
--> Jocelyn had 8 MORE books than Daphne.
Daphne had 20% fewer books than Jocelyn,
So, Daphne : Jocelyn --> 80% : 100%
20% --> 8 books,
Daphne --> 32 books
Jocelyn --> 40 books
Yan Ming --> 48 books

After Yan Ming bought some books,
Yan Ming's books : Jocelyn's books --> 3 : 2
Jocelyn's number of books remain the same --> 40
So, Yan Ming's books --> 40/2 x 3 = 60
60 - 48 = 12
Yan Ming bought 12 books.

cheers.

[MathIzzzFun]

superksmum:

Hi, help needed for these questions from Catholic High SA 2011


Ques 16) Jerry bought four times as many pencils as notebooks and spent a total of $21.60. He spent $2.40 more on the notebooks than the pencils. Given that a notebook costs $3.20 more than a pencil, find the cost of a pencil.


Thank you.

Q16 was discussed before - http://www.kiasuparents.com/kiasu/forum/viewtopic.php?f=69&t=280&hilit=Jerry+bought+four+times&start=4750

cheers.