Tutor MathsGuru: Ask me for your burning Maths questions!

[iFruit]

Daddy:

Hi,


I have 2 qn to ask. Thanks

1. A digital camera was selling at $480. After giving 20% discount, Kenny made an extra 20%. Find the cost price of the camera.


2. Junyang's saving and Weiming's saving are in the ratio of 3:8. If Weiming's saving is decreasing by 25%, their total saving will be $300. How much is Junyang's saving at first?

Thankss

1.

Selling price of camera = 8/10 x 480 = 384 (20% discount)

cost price = 10/12 x 384 = $320 (20% profit)

2.

Let Junyang's savings = 3u
Weiming's savings = 8u

After decreasing by 25%, Weiming's savings = 75/100 *8u = 6u

3u+6u = 9u = 300

Junyang's saving at first = 3u = 3 * 300/9 = $100


HTH

[pineapple tarts]

thank you very much tianzhu. It really helps a lot.

[tianzhu]

pineapple tarts:

thank you very much tianzhu. It really helps a lot.

Hi

You're welcome.

Best wishes

[Daddy]

Thank you iFruit

[ck123]

Anyone tried 2009 SCGS SA2 paper 1 Q28?


Question is:

The following figure shows a square piece of cardboard WXYZ. Four small squares of equal size and a circle, twice the area of each small square, were cut out from the cardboard. What percentage of the cardboard was cut out?

sorry but i don't know how to insert the diagram. Anyone came across this question? Please help :?:

Thanks

[Vanilla Cake]

ck123:

Anyone tried 2009 SCGS SA2 paper 1 Q28?


Question is:

The following figure shows a square piece of cardboard WXYZ. Four small squares of equal size and a circle, twice the area of each small square, were cut out from the cardboard. What percentage of the cardboard was cut out?
sorry but i don't know how to insert the diagram. Anyone came across this question? Please help :?:
Thanks

http://www.orlesson.org/orp/09Ma/2009-Math-SA2-SCGS.pdf
Assume side of 1 small square to be 1 unit
Side of the cardboard WXYZ will be 4 units for WX, XY, ZY and WZ.
Area of cardboard = 4 units x 4 units = 16 units²
Area of 4 small squares = 4 x 1 unit x x 1 unit = 4 units²
Since area of a circle = twice of area of each small square -> area of circle = 2x 1 unit x 1 unit = 2 units²
Total area that were cut out from the cardboard -> 4 smalls squares + 1 circle = (4+2) units² = 6 units²
6 units²/16 units²x100% = 37.5%
Percentage of the cardboard that was cut out = 37.5%.

[CJM]

1 Carton of marbles and 1/4 carton of golf balls cost $150.

3 Cartons of marbles and 11/16 carton of golf balls cost $130.

How much is the cost of 1 1/2 carton of golf balls ?

[CJM]

There are some coins in a box made up of 20-cent and $1 coins. There are thrice as many 20-cent coins as $1 coins. If the total amount of money in the box is $48, how many coins are there altogether ?

[iFruit]

CJM:

1 Carton of marbles and 1/4 carton of golf balls cost $150.

3 Cartons of marbles and 11/16 carton of golf balls cost $130.

How much is the cost of 1 1/2 carton of golf balls ?

1M + 1/4 G = 150

so,

3M + 3/4G = 450------->(1)

we also have

3M + 11/16G = 130 ------>(2)

From (1) and (2)

3/4G - 11/16G = 320

1/16 G = 320

3/2 G = 24/16G = 24x320 = $7680

That means you can get rich just by buying marbles

There is probably a typo somewhere in the problem.

[iFruit]

CJM:

There are some coins in a box made up of 20-cent and $1 coins. There are thrice as many 20-cent coins as $1 coins. If the total amount of money in the box is $48, how many coins are there altogether ?

Let number of $1 coins = u
Number of 20-cent coins = 3u

value of coins = u+0.2(3u) = 1.6u = 48

u = 48/1.6 = 30

Total coins = 4u = 120

HTH