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Quick alevel economics maths calculation problem

There was this question in my economics exam asking how much costs are left uncovered when total costs are £200000 and revenue covers 30% and a charity covers 12.5%

I did 200000 - 30% which was 140000
Then I did 140000- 12.5% which was £122500 (my final answer)

Some of my friends did 200000 - 42.5% and got 115000 which I understand but I don’t know why you get two different answers and would like to know which one is correct?

Thanksss
Reply 1
Original post by TheFlash2024
There was this question in my economics exam asking how much costs are left uncovered when total costs are £200000 and revenue covers 30% and a charity covers 12.5%

I did 200000 - 30% which was 140000
Then I did 140000- 12.5% which was £122500 (my final answer)

Some of my friends did 200000 - 42.5% and got 115000 which I understand but I don’t know why you get two different answers and would like to know which one is correct?

Thanksss

Sounds like your mates are correct. If the revenue covered 50% and a charity covers 50% youd expect it to be fully covered. Your method would mean 25% was still not covered.
Original post by mqb2766
Sounds like your mates are correct. If the revenue covered 50% and a charity covers 50% youd expect it to be fully covered. Your method would mean 25% was still not covered.


Sorry I don’t understand, the amount uncovered is what I’m trying to find but my answer (122500) isn’t 25% of the total costs. Please could you say where I went wrong with my calculation exactly as it seems alright to me
Reply 3
Original post by TheFlash2024
Sorry I don’t understand, the amount uncovered is what I’m trying to find but my answer (122500) isn’t 25% of the total costs. Please could you say where I went wrong with my calculation exactly as it seems alright to me

You apply the 12.5 percent to the remainder after the revenue cover has been subtracted. Really it should be applied to the original, total value. As you're therefore subtracting a smaller amount from the original total, your remaining costs are higher.
(edited 2 years ago)
Reply 4
The 12.5 % is not embedded into the 30 %, which you have done, they are separate %ages so you have to add them together then find use the sum of the percentages
(edited 2 years ago)
Original post by mqb2766
You apply the 12.5 percent to the remainder after the revenue cover has been subtracted. Really it should be applied to the original, total value. As you're therefore subtracting a smaller amount from the original total, your remaining costs are higher.


Okay I understand now, if the question was phrased ‘30% of the costs are covered by revenue and 12.5% of the remaining costs are covered by a charity’ then I would’ve been correct, that’s a shame
Reply 6
Original post by TheFlash2024
Okay I understand now, if the question was phrased ‘30% of the costs are covered by revenue and 12.5% of the remaining costs are covered by a charity’ then I would’ve been correct, that’s a shame

Yes, thats correct. Just one to watch out for in future.

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