Q&A - PSLE Math

[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.

[superksmum]

Hi MathIzzFun,


Really appreciate your help. Thank you so much for the explanation.

[Neat]

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.

[quote]Edureach[/quote]Appreciated :thankyou:

[jarenchuatw]

Thanks, BB for the answer…u made it look so simple.

[jarenchuatw]

These 2 P6 practice questions had me pulling my hair out, trying to figure how to solve it....apprecaite all the help out there, so that I can explain to my boy :stupid:


Q1 Raymond had 20% fewer stamps than Johnny. Lingling had 60% of the number of stamps Raymond had. Raymond gave 48 stamps to Lingling and both of them had the same number of stamps. How many stamps must Johnny give to Lingling so that both would have the same number of stamps? (Answer: 54stamps)

Q2 XiaoMing and Mary each had a certain number of comics. Xiao Ming gave away 40% of his comics and another 15% of his remaining comics to Mary. Then Mary gave 2/3 of her comics to Sally. Xaioming found that he had thrice as many comics left as Mary. If Mary had 210 comics at first,
(a) how many comics did Xiao Ming have at first? (Answer: 500)
(b) how many comics did Sally receive from Mary? (Answer : 170)

[szepinge]

Raymond 80% = 4u x 5 = 20u

Johnny 100% = 5u x 5 = 25u

Ling ling 3u x 4 = 12u
Raymond 5u x 4 = 20u

Make Raymond the same number of units
Repeated identity

Raymond must give 4u to ling ling so that both have 16 units
4U = 48
1u = 12
Ling ling have 16u now after Raymond give her 4u

Johnny must give 4.5 units to lingling
So that both have 20.5 units after that.

4.5 x 12 = 54 stamps

[Michaelia0816]

Yay! My exam marks was back, 30 for paper 1 and almost got a* by a few marks! Scoring super well in paper 2!

[Spongy]

Please help! thanks in advance.


There was a total of 820 boys and girls in a school hall. After 3/4 of the boys had left the hall and another 75 girls had entered it, there is now an equal number of boys and girls in the hall. How many more boys than girls were there in the hall initially?

[php]

Spongy:

Please help! thanks in advance.


There was a total of 820 boys and girls in a school hall. After 3/4 of the boys had left the hall and another 75 girls had entered it, there is now an equal number of boys and girls in the hall. How many more boys than girls were there in the hall initially?

After
Boy - 1u, Girl - 1u

Before - 4u, Girl - 1u - 75

4u + 1u - 75 --> 820
5u --> 820 + 75 = 895
1u --> 179

Before
Boy --> 4u = 4 x 179 = 716
Girl --> 1u - 75 = 179 - 75 = 104

Ans : 716 - 104 = 612