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Original poster

Maths question - Civil Service is wrong (we now have 100% more threads about the subject)

434 replies

Sharingaroomtinightthen · 02/08/2025 13:36

When I posted late last night I thought I’d get maybe half a dozen replies confirming the question didn’t have the correct answer and advising whether to tell the Civil Service recruiters. But here we are 1000 posts later.

https://www.mumsnet.com/talk/am_i_being_unreasonable/5384347-maths-test-to-think-civil-service-have-it-wrong

Maths question - Civil Service is wrong (we now have 100% more threads about the subject)
OP posts:
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7
TakeMeToAnIgloo · 02/08/2025 18:38

Amethystanddiamonds · 02/08/2025 18:01

I'd have gone for 150%. Increase in percentage from y1 to y2 is 200% (3x-x=2x). Then it drops by 1/4 (200/4=50). 200-50=150. But having read the answers I got confused and am now seriously doubting my maths ability.

It's not the percentage increase that drops by 1/4 though, but the actual circulation value at that point (so in your example, 3/4x). Your 2x-3/4x is 1.25x, which is 125% if you express as a percentage.

EligibleTern · 02/08/2025 18:20

Passportparanoia · 02/08/2025 18:17

You beat me to it!

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Turns out there was no point anyway as people are still arguing about it 😂

Passportparanoia · 02/08/2025 18:17

EligibleTern · 02/08/2025 13:40

Just (probably fruitlessly) reposting the screenshot from the calculator here: https://www.calculatorsoup.com/calculators/algebra/percentage-increase-calculator.php

You beat me to it!

Amethystanddiamonds · 02/08/2025 18:01

I'd have gone for 150%. Increase in percentage from y1 to y2 is 200% (3x-x=2x). Then it drops by 1/4 (200/4=50). 200-50=150. But having read the answers I got confused and am now seriously doubting my maths ability.

GinAndJuice99 · 02/08/2025 17:37

Dimondsareforever · 02/08/2025 16:28

Havnt seen the other thread … and not sure if I’m missing something. But the answer 450%?

Very simply - if it sold 10 in first year, then doubled in second year (20), then trebled (60), minus a quarter = 45.

The original 10 sold had increased by 450% by the end of the third year…..

Am I misreading the question? Don’t quite understand why all the fuss is about? And why would it need reporting??

So with your example, the question is how much has 20 increased by in percentage terms to get to 45?

The answer is 100% to double to 40 plus another 25% (5)

Meaning the answer is 125%. The test setter messed up

Samscaff · 02/08/2025 17:27

Sundaymorningcalla · 02/08/2025 16:20

Percentage increase is expressed as (change/original) x 100. So your answer is incorrect.

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You have made an error with your "start figure". We need the figure at the end of Y1, when it has already doubled, not the "original" figure from the start of Y1.

Original start no - 100
End of Y1 (after doubling during the year and reaching our start date) - 200
End of Y2 - 600
End of Y3 - 450

The change (increase) is 250 but you have put your start figure as 100 when it should be 200.

250/200 * 100 (to give us a % change from end Y1 to end Y3) = 125%.

SerendipityJane · 02/08/2025 17:20

fruitywineglass · 02/08/2025 17:15

But how would the student record their answer?

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Maybe that's the ingenuity test ?

Similar to "How can I answer this absolute bollocks question about my gender identity because there isn't a "What is this nonsense ?" option.

Who knows, by having the cojones to make this a long running series of threads on the UK premier parenting and right wing woke captured platform, maybe the OP will receive a tasty offer on Monday ?

fruitywineglass · 02/08/2025 17:15

Lemonsugarpancake · 02/08/2025 14:12

I haven't read the first thread, but perhaps it isn't a maths test but is designed to see if you speak up/ question authority etc?

But how would the student record their answer?

LegoLivingRoom · 02/08/2025 17:12

I am awful at maths (but good at literacy) and even I understand that it’s 125%.

Why are people sticking random % signs onto the end of their numbers when they are not percentages?

Samscaff · 02/08/2025 17:10

Truelyscrumptious21 · 02/08/2025 16:32

Okay let’s use a different number as a base

200

400

1200

900

Same calculation

Total sales difference 900-400 is 500

1 % difference from year 3 to year 2 is 9 minus 4 is 5

900/500 = 1.8

1.8 x 5 = 9

9 / 200 base = 4.5

4.5 x 100 =450%

All the other calculations don’t account for the number of sales increasing per 1% so they don’t use it in their final percentage increase.

Look try it with any number

50

100

300

225

225 minus 100 is 125

2.25 minus 1 is 1.25

225/125 = 1.8

1.8 x 1.25 =2.25 now because we started with 50 we times it by 2 and get 4.5 which x 100 is 450%

Look if it makes you all feel any better my DH and DC all think I am wrong too! They are adamant it’s 125% too.

Edited
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500 (the increase) as a % of your start point (200) is a 125% increase.

I think where you’re going wrong is in thinking that if you double a number it increases by 200%, when in fact it is 100%. If your salary increased from 40k to £80k that would be a 100% increase.

If sales doubled from 200 to 400 that would be a 100% increase. In fact they did a bit better than that, increasing not just by the same again (which would be 100%) but by one-and-a-quarter times. Which is 125%.

niadainud · 02/08/2025 17:03

MontyDonsBlueScarf · 02/08/2025 15:36

I'm thinking for next weekend's entertainment I might start a thread that depends on the difference between divided by and divided into.

Yes, anything containing the instruction "divide by a half" is sure to elicit several pages of innumerate nonsense responses similar to this thread.

Samscaff · 02/08/2025 17:01

You say we need to consider the initial circulation as 100% at the end of the first year.
At the end of the first year, the circulation doubled, so it became 200%.

This doesn’t make sense. Actually we don’t need to consider the doubling at all, because we are asked to calculate the % increase from the end of Year 1. The doubling during the first year should be disregarded - it’s a red herring.

The circulation increased from 200 to 450, an increase of 250.
250 as a % of our starting point of 200 is a 125% increase (if it had doubled to 400 that would have been a 100% increase, and it did a bit better than that.)

Reallybadidea · 02/08/2025 17:00

Ooothatsagoodone · 02/08/2025 16:48

To calculate the percentage increase in circulation from the end of the first year to the end of the third year, we need to consider the initial circulation as 100% at the end of the first year.
At the end of the first year, the circulation doubled, so it became 200%.
In the second year, the circulation trebled, equalling 600%.
In the third year, the circulation fell by a quarter, which means it was reduced to 75% of the previous year, resulting in 75% of 600% = 450%.
Therefore, the percentage increase in circulation from the end of the first year to the end of the third year is 450% - 200% = 250%.

You need to work out the percentage increase not just the change with a percentage sign after it!

SerendipityJane · 02/08/2025 16:56

OffOnOurHols · 02/08/2025 16:53

I think OP from some of the answers on this thread that it is evident that the standard of maths out there is appalling. I think I would have added another box to the end with the correct answer.

It looked like an online test, and the radio buttons suggest that you had to select an answer before being able to move on.

And we haven't seen the guidance.

niadainud · 02/08/2025 16:56

99bottlesofkombucha · 02/08/2025 14:20

Your title is wrong! Because it’s 200% increase from zero threads op. And before the Mumsnet maths mafia come at me to say 0 x 200% is 0, I remind them that zero is a special number.

I assume this is a joke?

OffOnOurHols · 02/08/2025 16:53

I think OP from some of the answers on this thread that it is evident that the standard of maths out there is appalling. I think I would have added another box to the end with the correct answer.

Samscaff · 02/08/2025 16:53

Dimondsareforever · 02/08/2025 16:28

Havnt seen the other thread … and not sure if I’m missing something. But the answer 450%?

Very simply - if it sold 10 in first year, then doubled in second year (20), then trebled (60), minus a quarter = 45.

The original 10 sold had increased by 450% by the end of the third year…..

Am I misreading the question? Don’t quite understand why all the fuss is about? And why would it need reporting??

An increase from 10 to 45 is not an increase of 450%. But that’s not what the question says happened with the figures, anyway! Yes, I’m afraid you are misreading the question.

Start with 10 at the end of Y1, if you like. Sales have already doubled, presumably from an absolute start number of 5, but we’re ignoring that because we’re being asked to calculate the increase from the end of Y1 to the end of Y3.

End of Y1 - 10
End of Y2 - trebles, so 30
End of Y3 - Reduces by a quarter, so 22.5

The increase is the difference between the end of Y1 and the end of Y3, which we were asked to express as a %. The difference is 22.5 - 10, which is 12.5.

12.5 as a percentage of our starting point (10) is 125%.

If your salary doubled, it would have gone up 100%. I expect you’d be happy to agree that if the sales in the question had doubled to 20, they would have gone up 100%. In fact they did a bit better than that.

Ooothatsagoodone · 02/08/2025 16:48

To calculate the percentage increase in circulation from the end of the first year to the end of the third year, we need to consider the initial circulation as 100% at the end of the first year.
At the end of the first year, the circulation doubled, so it became 200%.
In the second year, the circulation trebled, equalling 600%.
In the third year, the circulation fell by a quarter, which means it was reduced to 75% of the previous year, resulting in 75% of 600% = 450%.
Therefore, the percentage increase in circulation from the end of the first year to the end of the third year is 450% - 200% = 250%.

SerendipityJane · 02/08/2025 16:46

Bunnycat101 · 02/08/2025 15:22

You’d be wrong there about civil servants being rubbish at maths. There are some amazing analysts in the civil service doing incredibly clever data wizardry stuff in every department. ONS staff are civil servants as are HMRC staff. Staff working on the budget in Treasury likewise. Those departments will be very numerate.

Edited

So good at maths, but bad at humour ?

Merryoldgoat · 02/08/2025 16:46

Truelyscrumptious21 · 02/08/2025 16:43

Well that could be said of any of the answers! At least I have a shot at being awarded the points from the exam because 450% is in the drop down menu and 125% isn’t 😂

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Can you honestly not accept that there could be an error in the question given all of the people who have clearly explained why?

PeachPumpkin · 02/08/2025 16:46

I’m not that great at maths. It was a nice boost to have calculated the answer as 125% and see that so many others agree. Thanks OP and good luck!

Truelyscrumptious21 · 02/08/2025 16:43

Merryoldgoat · 02/08/2025 16:40

@Truelyscrumptious21

You can start with any number you like. If you don’t understand the maths you’ll never get the right answer.

Well that could be said of any of the answers! At least I have a shot at being awarded the points from the exam because 450% is in the drop down menu and 125% isn’t 😂

TeenToTwenties · 02/08/2025 16:42

Dimondsareforever · 02/08/2025 16:28

Havnt seen the other thread … and not sure if I’m missing something. But the answer 450%?

Very simply - if it sold 10 in first year, then doubled in second year (20), then trebled (60), minus a quarter = 45.

The original 10 sold had increased by 450% by the end of the third year…..

Am I misreading the question? Don’t quite understand why all the fuss is about? And why would it need reporting??

Wrong two ways.

First they want to base on the end of the first year, not the start.

Then they want percentage increase, which is (new-original)/original x 100 and not new/original x 100%.

Merryoldgoat · 02/08/2025 16:40

@Truelyscrumptious21

You can start with any number you like. If you don’t understand the maths you’ll never get the right answer.

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