Tutor MathsGuru: Ask me for your burning Maths questions!

[starlight1968sg]

Dharma:

Total cost of N books = $8N

Total cost of (N+1) books = $10(N+1)

$10(N+1) - $8N = $18
$2N = $18 - $10 = $8
N = 4 (No. of books bought by Jane)

yes, the ans is 4. Without the use of equation method, how can we solve it using model? I have been trying this p5 question for days!
MTIA.

[CoffeeCat]

The average price is $8 . The extra value that causes the increase in average price across all books (including the new book) is $18-$10=$8.

since this extra$10 increases theaverage prices of all books by $2, there are 10/2=5 books.(including the new book).

[Vanilla Cake]

starlight1968sg:

Jane bought a number of books at an average price of $8. If she decides to buy another book which cost $18, the average price of all the books will become $10. Find the number of books she bought?

It is a p5 Maths question.

Hi starlight1968sg,
For info and there is a helpful http://psle2010a.blogspot.com/2010/03/mathsp5averagea001.html that provides solutions for Maths questions. Your question has been selected and two different methods without using algebra have been used to solve it.

[starlight1968sg]

Hi folks,

Thanks so much for helping me.

[firebird]

Dear Maths guru


Good morning.

Kindly help me with this question please:

1) Bag X and Bag Y contained some marbles. Bag X had 304 marbles fewer than Bag Y. After 52 marbles from Bag X were taken out and put into Bag Y, there were five times as many marbles in Bag Y as in Bag X. How many marbles were there in Bag Y at first?

I was reasonably sure of getting this answer correct. My answer was 464 marbles.

However, the given answer is 458 marbles. I do not know where I have gone wrong.

Many thanks
firebird

[mathsguru]

firebird:

Good morning Mathsguru


Please help me on the following P6 maths:

1) Clement had a wooden block measuring 50cm by 70cm by 90cm.
He wanted to cut out some little cuboids measuring 2cm by 3cm by 4cm.
What is the minimum amount of wood wasted?

Given answer is 360cm cuboids. I am getting 180 cuboids. Please help.

2) Micheal asked his classmate what time it was.
Jackson, the math whiz, replied with a cheeky grin,
\"It's 2000 hours, 1990 minutes and 1980 seconds before midnight?
Can you help Micheal find out what time it is?

I am totally lost.

Thank you
firebird

Hi Firebird,

Sorry for the delayed response. Here are my solutions for your reference.


MathsGuru

http://www.postimage.org/image.php?v=PqlTejJ

http://www.postimage.org/image.php?v=PqlTgOS

[mathsguru]

firebird:

Dear mathsguru


Please help me on the following P6 maths:

1) Sophie and Rachel share blue ribbons in the ratio of 5 : 2.
They want to buy some red ribbons so that the total number of ribbons they have will be tripled. In what ratio must they divide the red ribbons so that Rachel will have twice the number of ribbons she has now?

I got 17:4. But the given answer is 6:1.

2) Faizal has a rod. He needs 6 minutes to saw it into 4 pieces. How many minutes does he need to saw the rod into 28 pieces?

I got 42 minutes. But the given answer is 54 minutes

3) Customers were given a free CD for every 2 CDs they buy at a sale.
Ben spent $K and got 30CDs in all. WHat is the price of 1 CD?

I got $K/20. But the given answer is $K/10

4) There were some horses and people on a farm. There were 62 more legs than heads. There were 26 more heads than tails.

a) How many people were there?
b) How many horses were there?

I really do not know where to start for question 4 a) & b)

5) Sugar and water are mixed in the ratio 1:5 to make syrup. The volume of the syrup is 800 cm3.

a) Find the volume of sugar in the syrup.
b) Find the volume of water in the syrup.
c) How much more sugar must be added to the surup so that the ratio of the sugar to water in the syrup becomes 1:3?


a) I got 133 1/3 Cm3 But given answer 13 1/3 CM3. I hope i am right.
b) I got 666 2/3 cm3 and the given answer also 666 2/3 cm3.
c) I got 1,866 2/3 cm3 But the given answer 88 8/9 cm3


Many thanks
firebird

Hi Firebird,

Here are my solutions. Hope they help!


MathsGuru

http://www.postimage.org/image.php?v=PqlTthA

http://www.postimage.org/image.php?v=PqlTygS

http://www.postimage.org/image.php?v=PqlTAM0

http://www.postimage.org/image.php?v=PqlTDg9

http://www.postimage.org/image.php?v=PqlTFLi

[mathsguru]

starlight1968sg:

Hi,

I need some help.

Jane bought a number of books at an average price of $8. If she decides to buy another book which cost $18, the average price of all the books will become $10. Find the number of books she bought?

It is a p5 Maths question.

MTIA.

Thanks for pointing out my glaring typo error!

Hi Starlight1968sg,

Here's my explanation. Hope it's clear enough.


MathsGuru

http://www.postimage.org/image.php?v=gxzL7ai

[mathsguru]

firebird:

Dear Maths guru


Good morning.

Kindly help me with this question please:

1) Bag X and Bag Y contained some marbles. Bag X had 304 marbles fewer than Bag Y. After 52 marbles from Bag X were taken out and put into Bag Y, there were five times as many marbles in Bag Y as in Bag X. How many marbles were there in Bag Y at first?

I was reasonably sure of getting this answer correct. My answer was 464 marbles.

However, the given answer is 458 marbles. I do not know where I have gone wrong.

Many thanks
firebird

Hi Firebird,

Here's my solution. Drawing a model would make this question much easier to understand. Hope it helps!


MathsGuru

http://www.postimage.org/image.php?v=aV5FlQ9

[rain29]

Hi mathsguru,


Thanks for your help.