Tutor MathsGuru: Ask me for your burning Maths questions!

[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.

[Daddy]

Thank MathIzzzFun…

[lazy me]

Hi math guru,

Pls help me with this question:

There were 450 plastic chairs n metal chairs at a furniture store. After 60% of the plastic chairs n 1/6 of the metal chairs were sold, the total number of chairs left was 232. How many plastic chairs were sold?

[jieheng]

lazy me:

Hi math guru,

Pls help me with this question:

There were 450 plastic chairs n metal chairs at a furniture store. After 60% of the plastic chairs n 1/6 of the metal chairs were sold, the total number of chairs left was 232. How many plastic chairs were sold?

---------at a store--------sold---------left
PC---------5u--------------3u------------2u
MC---------6p--------------1p-----------5p
Total-----450-------------218----------232

1p + 3u --> 218
6*(1p + 3u) --> 6*218
6p + 18u --> 1308
6p + 5u + 13u --> 1308
450 + 13u --> 1308
13u --> 858
1u --> 66

Number of plastic chairs were sold = 3u = 3*66 = 198

[nnchia]

Hi, need help on this question:-


Mrs. Tan bought 4 times as many toy guns as teddy bears. She spent $1750 altogether. A toy gun cost $10 less than a teddy bear. The total cost of toy guns was $490 more than the total cost of teddy bears.
(a) How much did Mrs. Tan spend on the teddy bears?
(b) How much did on teddy bear cost?

(Answer: (a) - $630, (b) - $18)

I could solve this via algebra but very lengthy so looking for a simpler solution! Thanks!

[jieheng]

nnchia:

Hi, need help on this question:-


Mrs. Tan bought 4 times as many toy guns as teddy bears. She spent $1750 altogether. A toy gun cost $10 less than a teddy bear. The total cost of toy guns was $490 more than the total cost of teddy bears.
(a) How much did Mrs. Tan spend on the teddy bears?
(b) How much did on teddy bear cost?

(Answer: (a) - $630, (b) - $18)

I could solve this via algebra but very lengthy so looking for a simpler solution! Thanks!

toy guns 4u
teddy bears 1u

total cost of teddy bears (1u) = (1750 - 490) / 2 = 630

a) the amount of money that Mrs. Tan spend on the teddy bears is $630

total cost of toy guns (4u) = 630 + 490 = 1120

the cost of toy guns (1u) = 1120 / 4 = 280

Difference between the cost of 1u of teddy bears and toy guns
=630 - 280
=350

Given the difference between the cost of 1 pc of teddy bear and toy gun
=10

No of teddy bears = 350 / 10 = 35

the cost of one teddy bear = 630 / 35 = 18

b) the cost of one teddy bear is $18

[nnchia]

Thank you so much for your reply!

[lazy me]

Tq jieheng for ur help!

[Herbie]

Hi! I need help in this qn.


In how many years will a sum double itself at 7.5% simple interest?
Tq