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?

It's definitely 125

I knew someone would notice this and I did question it myself.

I didn’t say ALL CHANGES are compared to the base number of 100. I followed the wording of the question. ‘The next year circulation trebled before falling by a third’.

I agree it is ambiguous but I believe the implication here is that it fell by a third AFTER it had trebled.

The wording at the beginning of the question, on the other hand, does not in any way indicate that it trebled after it had doubled.

(Hence why my method appears ‘erroneous’)

True. But you’re still wrong.

Ignoring that you've disapplied the meaning of words to get to those figures, the percentage increase from 100 to 225 is 125%.

It has gone from £10 to £22.50. It has increased by £12.50, that is 125%.

You typed ‘The next year circulation trebled before falling by a third’. Cleverly omitted the last 3 words in the sentence. Why do you do this? It isn't a good troll anyway. Deftshaker has you beat.

The number of YABU votes will increase in direct proportion to the number of times the correct answer is stated and explained! We are onto a losing streak here.
I now believe the stats about the average reading age in the UK - age 9.

It's obvious the increase is of 125% and the current figure is 225% of the end od year 1 figure.

Whoever wrote this question can't articulate it in English properly.

There is only one correct answer in maths, there should be no dilemma running into 24 pages on MN.

It's wrong OP, you are correct.

If we are only asked by the INCREASE - the difference between the starting number and ending number - then it's 125%
Assuming:
circulation at end of year 1 is 100
circulation at end of year 2 is 300
circulation at end of year 3 is 225

The INCREASE between end of year 1 and end of year 3 is 125 = 125%

TOTAL Circulation at end of year 3 is 225% of end of year 1 circulation

I agree it is awful that the right answer is not an option. But it is funny seeing so many people arguing that the OP is wrong. Not understanding it is one thing but being so confidently incorrect is another.

Whilst you are correct in your answer of a 125% increase, your starting point is always 100% which you then deduct for the difference. How else would you calculate a percentage loss for instance?

I think you are confusing this with the 100% increase in the first year which is a coincidence and entirely separate.

Went to bed last night and there were 200 posts
Now there's about 700

So there are 500 more posts. The number of posts has increased by 500.
A 100% increase would be 400 posts (200 more)
A 200% increase would be 600 posts (400 more)
A 250% increase would be 700 posts (500 more)

(700 - 200)/ 200 = 2.5

You're right. Not sure if I mis-typed or misremembered so apologies for that. However, I followed the reasoning given (that the trebling was of the original number, not a trebling of the number at the end of Year 1) and 225% is the correct answer. The question is unfortunately ambiguous.

In the first year 200 newspapers sold
In the second year 600
In the third year 450

And theincrease from 200 to 450 is an increase of 125%

But in the first year 200 sold
In the period from the end of year one to the end of year three 1050 newspapers sold!!
Percentage increase from 200 to 1050 =
a way for a politician to spin a bad year!!

May be wrong but id also agree it’s 225%

I assigned letters so as follows….

Starting point is Y
end of year 2 you have 3Y
at end of year 3 to reduce by a 1/4 you get 2.25Y

so the multiplier is 2.25 no? The starting point is not nothing, it has a value.

I agree with you OP. I also ran the question through ChatGPT to check as all the posters disputing made me question my sanity. ChatGPT agrees with you too.

So it has increased from Y to 2.25Y. Therefore it has increased by 1.25Y.

The multiplier is 2.25, the increase is 1.25Y, no?

The circulation has increased by 225% from EoY1 to EoY3

But that isn't what the question asks, it asks for the increase in circulation as a %. OP is right.

If I pay you £1000 and then multiply it by 2, I get £2000

What percentage has your pay INCREASED by?

I think it's a poorly worded question. It's clear the answer they are after is 225% as 200*225%=450 (using OP's guide figures) so none of the other answers fit when you take year 1 out of the reckoning. But the term percentage increase does suggest 125%.

Yes I think your right

In a previous role I used to manage data that was reported in the press and used to have similar arguments with our media team every month.

They couldn’t get their heads around how something could be correctly reported as a four-fold increase AND a 300% increase.

Generally we tried to stop using % growth for anything over 100% because so many people struggled with it.

It seems quite intuitive that 10% growth takes you from £100 to £110 but if you get to 110% growth there’s always someone who thinks the answer is £110.

Gemini AI agrees with you (I don’t think anyone’s posted this yet but sorry if they have)
The percentage increase in the circulation of News Today from the end of the first year to the end of the third was 125%.
Here's a step-by-step breakdown of the calculation:

1. Assume the circulation at the end of the first year was 100 units.
2. In the second year, the circulation trebled, so it became

100 units. times3 = 300

1. In the third year, the circulation fell by a quarter, which is a decrease of

300 times frac14 = 75 units. The final circulation was 300 - 75 = 225 units.

1. The total increase from the end of the first year to the end of the third year was

225 - 100 = 125 units.

1. To find the percentage increase, divide the total increase by the starting circulation and multiply by 100:

125

• × 100% = 125%

100

I wish the people who have realised that OP is correct, and those who have just joined the thread this morning and realise that the OP is correct, would vote YANBU. Because the current vote percentage is an absolute embarrassment.
If you voted YABU and want to change it you can easily do that.
I must say I was impressed that Horsie actually accepted they were wrong, after a series of increasingly bonkers posts. Have an extra apple.🍎

I am simply stunned that the poll currently stands at

YABU 60%
YANBU 40%

with 406 votes

That 60% of people who voted must have initially got the answer to this question wrong is quite staggering.

Well, either that or they thought she was BU for wanting to make a complaint about the incorrect answer.