Maths test - to think Civil Service have it wrong?

[Sharingaroomtinightthen]

I’ve just applied for a Civil Service test. Part of it is passing a numerical test.

This is the question.

The answer is 125%. I’m sure of it.

If you start with £100, and in the first year it doubles it’s £200. So at the of year one it’s £200.

In year two it trebles to £600.

It then falls by a quarter in the third year to £450.

So end of year 1 - £200.

End of year 3 - £450.

It’s increased by 125%.

125% isn’t an answer option.

WIBU to email and tell them they’ve got it wrong?

You need to forget anything at all to do with the number 100. Anything and everything.

You said you started with 100. As per the question, this doubled by the end of year one. So at the end of year one, the number is 200.

200 is your starting figure. 100 is irrelevant and features nowhere in working out the answer to the question.

The question is about percentage increase not actual amount of 200. So 225% correct

They are outsourced to a third party. And @Sharingaroomtinightthen cannot be offered a job based on initial sift test, it is literally the test to be allowed to apply. Sad fact is, if you get it wrong, there is no recourse, regardless of whether the question is poorly phrased although I’d have gone 225% personally but clearly a lot of others have had doubts.

People have toiled through the night on this thread, the die hard 225%ers have mostly conceded. I would do yourself a favour and join the 125s now.

But the question is not to calculate from base. It’s from the end of year one to the end of year three. And whichever way you calculate it it’s 125%.

Is the trebling a trebling of the previous year's end-of-year circulation or of he end of Yr1's? My friend also has a Maths degree and that's been her line of work for 40 years - finance, pensions, actuarial work, tax - so yes, she knows her Maths. It's the English in the question that's the main problem because the meaning is unclear.
*Edited for typo.

Year 1 - 100 papers.
Year 2 - it triples to 300 papers

That is an increase of 200%

Year 3 - it drops by a quarter, to 225 papers.

A drop of 25% vs the end of year 2, but still a 125% increase since year 1

I think that one of the thung you might be doing is treating these as new sales, so that you're adding the 225 and the 300 you the 100, and getting a figure of 625 (I think the highest you gave was 650).

This isn't how the question is written but if these were new subscriptions on top of existing papers in circulation, that would be % growth of 525%.

I’ve asked my son who is doing a masters in maths. He said it’s 125% OP

Nope. The numbers don’t matter you can use any number for the circulation at the beginning of year one - the base. To keep it simple start with 100 as the base circulation which increases by 100% to 200 at the end of year one, then trebles to 600 by the end of year 2. Then a 25% reduction of the whole reduces that number to 450 by the end of year 3. Subtract the end of year 1 number of 200 from the end of year 3 number of 450 = 250. Divide 250 by the 200 circulation figure at end of year one = 1.25. Multiply by 100 to get the % change = 125%

But if it was to calculate the % difference from end of year 1 to 2 using the base what would your answer be? That’s what I am asking because 450% is the only answer on the drop down that fits.

I am giving up now anyway. I can only see 450% being the correct answer. I am dumb. I accept that.

I got 125%. Maths isn’t my strongest subject so I asked DH who is an accountant and he got the same answer.

I’m in funds management with a maths degree and I’d send that straight back if that was our performance calculation. Which it wouldn’t be because the clients aren’t silly either and they would leave if we made errors like that.

horsie should start estimating arithmetically the value of 0 to the power of 0. They will love that.

It is a question from the Civil Service Numerical Reasoning Test, used in some recruitment campaigns.

Hi OP. I haven't read the whole thread, only your replies. I work in the government statistical service (civil service) and based on how the question is worded then the answer should indeed be 125%.....

I agree that by saying 'percentage increase' then going from say 100 to 200 would be a 100% increase. And then work the logic from there.

So 200 to 450 is a 125% increase.

This is how language is used in say shares too: If the value of your BP shares goes from £3 a share to £6 a share, thats a 100% 'increase' (not 200%).

I'd let them know. Or I'm happy to help let civil service HR know. At least 125 and 225 aren't both there as answers!

Only if you calculate it correctly. 56% of poll voters calculate it incorrectly, as does the test author. Apparently due to a failure of comprehension. Although the OP itself is ambiguous. As others have said, are people voting that the correct calculation is incorrect, or that the OP should not report the error?

Send what back? I'm not sure if you were replying to my comment or something previous.

The question is perfectly clear - calculate the % increase from end of year 1, so 100% increase to 200 in year 1 which trebles to 600 in year 2. It’s not the English that’s at fault, it’s the fact that the correct answer doesn’t appear as an option.

well, I'm no mathematician, as someone is sure to point out 😃 but I get 225%

let's say the starting circulation is 10 (copies)
End of year 1= 20 copies (doubled.)
End year 2 - 60 copies (tripled)
End year 3 - 45 copies (3/4 of 60, as it fell by a quarter)

Difference between end year 1 and end year 3 - 45 divided by 20 = 2.25

x 100 to give a percentage

making 225%

====

I failed my civil service entrance exam. Is this why 😂

I'm a retired maths teacher with a degree and a PhD in maths. I reasoned the question as follows:

doubled, trebled, down a quarter = 2 x 3 x 0.75 = 4.5 = 450% = 350% increase, but that's not one of the answers. Try again.

From end of first year: 3 x 0.75 = 2.25 = 225% = 125% increase. So I agree with @Sharingaroomtinightthen , and that's not one of the answers!

There's no fool like an old fool, so it's quite possible I've misunderstood the question, but I think there's an error, and that the question should say something like, "What is the circulation [at the end of whichever period you choose] as a percentage of the original amount."

Bloody hell, this post has got more attention that the ones which say stuff like, "What do blokes do that gives you the ick?", which is saying something.

@ApplesinmyPocket
Percentage increase is calculated as (new-original)/original x 100%
So in this case with your numbers ( 45-20)/20x100% = 125%.

It's not perfectly clear though. It doesn't specify whether it trebles from the original figure or from the end of Yr1 figure. People on here are making assumptions and refusing to see that there are other equally valid ways to read the question. It is fascinating to see how entrenched people can become!

You missed a step. When you arrive at the end of year figure of 45, you then subtract the 20 copies from end of year 1 = 25. So it’s 25, not 45 divided by 20 = 1.25 x 100 gives 125%.

I don’t follow your logic at all. I think you are confusing matters by labelling the years differently from what they are called in the question.

The question asks about the increase from end Y1 to end Y3.
Start Y1 - call it 100.
End Y1 - this is our starting point for the calculation required. Sales have doubled, so 200.
End Y2 - Sales have trebled, so 600.
End Y3 - Sales have reduced by a quarter, so 450.

We are asked to calculate the % increase from end Y1 to end Y3. Sales have increased from 200 to 450 in this time, an increase of 250.

If sales had doubled, i.e. increased to 400, that would have been a 100% rise, but they did a bit better than that - they increased one-and-a-quarter times, which is 125%.

Even my very aged brain agrees it is 125%. Reading all the alternative posts has brought me to the conclusion that lots of people aren't very good at working out percentages and/or, more importantly, didn't read the EXACT wording of the test question before they started, so go down a blind alley of calculating using the wrong figures in the first place. We were always read the exam question properly and think about it carefully.

No, you are wrong from the sentence beginning Difference between..
It should read as follows:
Difference between end year 1 and end year 3 is 45 - 20 (a subtraction) which is 25.
To get the percentage increase you put that number over the end year 1 number and multiply by 100
25/20 X 100 = 125