Tutor MathsGuru: Ask me for your burning Maths questions!

[NYPSkiasuparent]

atutor2001:

suiyuan:

Hi
Thank you for your offer.

1)During a warehouse book sale, Sally spent 62.5% of her money on 24 books and 18 pens. She also spent 25% of her remaining money on 18 files. Each pen costs 8/9 as much as the price of one book. The file costs $7.80 less than a book. Find the total cost of one book and one pen.

2)Mr Lim spent $1496 on some comics and dictionaries altogether. The number of comics bought to the number of dictionaries bought was in the ratio of 3 : 2. A dictionary cost $4 more than a comic. The total cost of the comics was 20% more than the total cost of the dictionaries. Find the cost of a dictionary.

Hi suiyuan

You are very \"naughty\". But the 2nd question is a bit easssy!

Regards

Why is she naughty?

[jkids]

hi maths guru

I need some advice, not on problem sums but rather can you recommend an enrichment centre for my child? he is weak in maths, others subjects lik eng and Chinese is ok. recently he failed his maths, got 27/70

he seem to have prob understanding the math q, esp prob sums. what goes wrong, I really duno. we need to explain a few times, but sometime he still dun get it. he only has eng tuition but we intend to withdraw him fr eng class and enrol him for math class. can you recommend? I saw a few...cma , mind matter, mind stretcher...but dun really noe which is a better one...

thanks..

[milo-cupcake]

Hi Maths guru,

This is my DD recently SA1 Maths question. My DD and her classmates answer was 180 but the answer given by the teacher was 120. Please can you tell whose answer is correct?
Thanks in advance!

http://i44.tinypic.com/30igcd2.jpg\">

[MathIzzzFun]

milo-cupcake:

Hi Maths guru,

This is my DD recently SA1 Maths question. My DD and her classmates answer was 180 but the answer given by the teacher was 120. Please can you tell whose answer is correct?
Thanks in advance!

http://i44.tinypic.com/30igcd2.jpg\">

in both cases, the fraction refers to the original number as whole, so the answer is 120

However, if the second sentence is:\"On the second day, he sold 1/3 of the remaining watermelons....\" then the answer will be 180

cheers.

[Arrmanas]

450 - (2/5 x 450) - (1/3 x 450) = 120


The tricky part is "1/3 of his watermelons".

If the question says "1/3 of the balance watermelons" then the last calculation would be [1/3 x ((450 - (2/5 x 450)) = 90]. This gives 180 as the answer.

[acehkr3009]

Hi I have this p5 question & will like to know if there is any solutions other than model/graphical method…Thks


6A & 6B have the same number of pupils each. The ratio of the number of boys in 6A to the number of boys in 6B is 1:3. The ratio of the number of girls in 6A to the number of girls in 6B is 4:1. What is the ratio of the number of girls to the number of boys in 6B?

[Daddy]

Hi mathguru,


I have question to ask. Thanks.

Mitchell and Aaron had $720 altogether. Mitchell gave 1/7 of his money to Aaron. In return, Aaron gave 1/4 of all the money he had to Mitchell. Then they both had an equal amount of money. How much did Mitchell have at first?



Daddy.

[Daddy]

Hi mathguru,


I have question to ask. Thanks.

Mitchell and Aaron had $720 altogether. Mitchell gave 1/7 of his money to Aaron. In return, Aaron gave 1/4 of all the money he had to Mitchell. Then they both had an equal amount of money. How much did Mitchell have at first?



Daddy.

[Daddy]

Hi mathguru,


I have question to ask. Thanks.

Mitchell and Aaron had $720 altogether. Mitchell gave 1/7 of his money to Aaron. In return, Aaron gave 1/4 of all the money he had to Mitchell. Then they both had an equal amount of money. How much did Mitchell have at first?



Daddy.

[MathIzzzFun]

Daddy:

Hi mathguru,


I have question to ask. Thanks.

Mitchell and Aaron had $720 altogether. Mitchell gave 1/7 of his money to Aaron. In return, Aaron gave 1/4 of all the money he had to Mitchell. Then they both had an equal amount of money. How much did Mitchell have at first?



Daddy.

work backwards... the total amount remains the same regardless of the number of transfers between the two...eg. A and B has $200 altogether. After A gave $40 to B, they have equal amount of money.. so, we know that they have same amount after the transfer ie each had $100. So, before the transfer (A gave $40 to B), A had --> $100 + $40 = $140, B had $100- $40=$60. This is the basic step in working backwards.

I am showing the thought process in the following..

In the end (after Aaron gave 1/4 of his money to Mitchell),
Mitchell --> $360
Aaron --> $360 ---- ask : what fraction of Aaron's money was left in the end ? --> 3/4 of the amount before he gave 1/4 to Mitchell.

So, $360 --> 3/4 of Aaron's money before transfer.
1/4 of the Aaron's money before transfer --> $ 360/3 = $ 120

Before the Aaron's transfer OR after Mitchell gave 1/7 of her money to Aaron,
Aaron --> $360 + $120 = $ 480
Mitchell --> $360 - $ 120 = $ 240 -- again, ask : what fraction of Mitchell's money does this represent ? --> 6/7 of Mitchell's original amount, since she gave 1/7 to Aaron.
$240 --> 6/7 of Mitchell's original amount
1/7 of Mitchell's original amount --> $240/6 = $40

At first,
Mitchell's money --> $240 + $40 = $280
Aaron's money --> $720 - $280 = $440


cheers.