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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
niadainud · 03/08/2025 09:46

Merryoldgoat · 03/08/2025 00:22

I don’t want it to be 125% - it is.

I do this for a living. I’m an accountant and calculating percentage changes is something I do on a daily basis. If I didn’t know what I was doing it would’ve been discovered by now given my work is scrutinised, analysed, and used to make significant financial decisions every workday.

The question setter either doesn’t understand what a percentage change is, or worded the question incorrectly.

The answer to the question as worded is 125%

It’s entirely possible that the setter intended the answer to be 450% but they asked the wrong question if that’s the case.

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I guess it's entirely possible the question setter wanted the answer to be 42, or "To get to the other side," given that none of the possibilities they've provided is actually correct!

Seriously though, I suspect the question has been tweaked at some point and they forgot to amend the answers.

niadainud · 03/08/2025 09:40

Merryoldgoat · 03/08/2025 00:12

What - you think the laws of mathematics are somehow subjective?

🤣

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Yes, I was about to pick up on "Not for this question" as well.

It's quite astonishing.

niadainud · 03/08/2025 09:36

Spiderbitebatbite · 02/08/2025 23:39

My answer clearly demonstrates how I get to 450% over and over using different numbers the answer is always 450%. Just like others have bravely said and been berated for. There is an answer for 450% on the test which is an option for those of us who know how to work it out correctly would choose.

450% is the right answer.

Surely you can see if sales have trebled after year 2 the answer must be above 300% as a starting point! Work from there. I mean I concluded this after quickly reading the question.

The answer is 450% all you sheep can keep harping on about it being 125 % it won’t change the fact you are wrong and the glaringly obvious exclusion of this even being an option to pick says it all.

Edited
Show quote history

all you sheep can keep harping on about it being 125 % it won’t change the fact you are wrong and the glaringly obvious exclusion of this even being an option to pick says it all.

Are you by any chance also a conspiracy theorist? 🤔

niadainud · 03/08/2025 09:32

Spiderbitebatbite · 03/08/2025 00:58

@ItsFineReally That is not correct the increase in circulation from

200 to 600 is a 400 increase in circulation which represents a 300% increase this means the final answer must be above 300%

Next year circulation decreases by 25% so 400-100=300

300 is an increase of 150% from the starting point of 200 so

300% plus 150% is a 450% increase

The correct answer is 450%

Edited

the increase in circulation from 200 to 600 is a 400 increase in circulation which represents a 300% increase this means the final answer must be above 300%

No, it's a 200% increase.

Next year circulation decreases by 25% so 400-100=300

This is correct.

300 is an increase of 150% from the starting point of 200

No, 300 is 150% of 200, not an increase of 150%. They are not the same thing.

You have not understood how to work this out AT ALL.

niadainud · 03/08/2025 09:25

Spiderbitebatbite · 02/08/2025 23:50

@NoCommentingFromNowOn

50

As question states start at 100 after doubling 50

100
300
150

300 - 100 = 200 which represents 300%

200 minus 25% is 150 which is a 150% increase from 100 start

300% plus 150% is a 450% increase

The answer is 450%

Edited

As question states start at 100 after doubling 50

What does this mean? Where does the question state to start at 100?

(Answer: it doesn't.)

NoCommentingFromNowOn · 03/08/2025 09:20

Spiderbitebatbite · 02/08/2025 23:50

@NoCommentingFromNowOn

50

As question states start at 100 after doubling 50

100
300
150

300 - 100 = 200 which represents 300%

200 minus 25% is 150 which is a 150% increase from 100 start

300% plus 150% is a 450% increase

The answer is 450%

Edited

Err I don’t follow that!

The answer is 125, I’m happy with that, I’m just suggesting the numbers look easier to deal with if you start with 50!

niadainud · 03/08/2025 09:14

Spiderbitebatbite · 02/08/2025 23:09

100

200
600
300

As the question states starting from 200 after the 100 is doubled.

Treble Increase from 200 to 600 is 400 which represents 300% increase in year 2.

25% decrease in year 3 so 400 minus 25 % is 300 which is an increase of 150% from year 2 starting point of 200.

300% plus 150 % equals 450%

You can use any number with my logic above and it always comes out as 450%.

200

400
1200
1000

As the question states starting from 400 after the 200 is doubled

Treble increase of 800 which represents the 300% increase in year 2.

25% less of 1200 total increase in year 3 so 1000 which is an increase of 150% starting point of 400.

Again 300% plus 150% is a total of 450% increase.

IMO the question clearly states the numbers in circulation trebled so the answer has to be above 300% anyway. When calculating the final increase accounting for a 25% decrease the answer is 300% plus 150% which is 450% which, conveniently for me I would have chosen and got right.

All you who keep spouting 125% is the right answer are wrong maybe that’s why there isn’t an option for it! You all remind me of sheep to the slaughter!

Edited

Why is it the posters offering the longest, wordiest, most rambling explanations always come up with the wrong answer?

Eachpeachpearplumm · 03/08/2025 09:09

They also need to use a comma after the fronted adverbial.

Bunnycat101 · 03/08/2025 09:06

I really hope spider is trolling now. This thread just keeps on giving.

Merryoldgoat · 03/08/2025 08:42

Tryingtokeepgoing · 03/08/2025 08:01

That’s not how percentages work 😂

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I read those workings again and honestly thought I might be having a stroke.

It takes quite a talent to wholly fudge a problem so very comprehensively.

Tryingtokeepgoing · 03/08/2025 08:01

Spiderbitebatbite · 03/08/2025 00:26

@ItsFineReally

100 doubles to 200

As the question states start at 200 in year 2

200 trebles to 600 so a difference of 400 which REPRESENTS a 300% increase this is the starting point HINT the answer must be above 300% it is clear as day and spelt out in the question!

In year 3 there is a 25% DECREASE in circulation so 400 circulated in year 2 so this figure minus 25% is 300

300 is a 150% increase from the starting point of 200

so 300% plus 150% is 450% increase

The correct answer is 450%

Edited

That’s not how percentages work 😂

Biskieboo · 03/08/2025 07:59

I'm a bit worried. My boss has said my pay will soon be increasing by 10%. I was happy because I thought this meant it would go from £50k to £55k. But according to spidermaths it looks like it'll be actually be going to £5k. Do I need to ask for a 110% increase to get from £50k to £55k?

WallTree · 03/08/2025 07:31

Spiderbitebatbite · 03/08/2025 00:07

The clue is in the word represents! The key is in the fact that trebling represents a 300% increase.

I mean it’s so clear. I demonstrated how I got to 450% using the 50 starting point you wanted me to.

I can’t make it any clearer if you don’t grasp the basics.

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Trebling a number is a 200% increase. Treble 1 and you get three. That is an increase of 2, not 3.

WallTree · 03/08/2025 07:19

Sundaymorningcalla · 02/08/2025 16:18

Percentage increase is expressed as (change/original) * 100

Change is (1 x 3 x 0.75 / 1) x 100 which is 225%

Edited
Show quote history

You've missed a step in calculating the change.

it's (1x3x0.75)-1

i.e. It's the increase (2.25) minus the original (1)

miraxxx · 03/08/2025 03:39

Spidy is the Bgassfraudfruad fella from the previous thread. Both are magnificent trolls.

Team125 · 03/08/2025 03:30

Spiderbitebatbite · 03/08/2025 00:52

@Sharingaroomtinightthen

8 doubles to 16

As the question states start from here

16
48
24

48-16 is 32 which represents 300%

decreases by 25% which is 32 - 8=24. 24 is 150% increase from the starting point of 16.

so 300% plus 150% is 450%

The answer is 450%

😂😂😂 this is gold!

If you’re a troll then you’re a genius!

If you genuinely think this is how maths works then I fear for how you get by in life 🤣

Samscaff · 03/08/2025 03:12

@Spiderbitebatbite

I'm afraid you are making yourself look very silly.

You seem to be under the impression that doubling a number increases it by 200%. It doesn’t. It increases it by 100%, i.e. the same again.

If your salary doubles, the new salary total is 200% the size of the old total - but the % increase is 100%.

Saying that because the total trebles at one point in the calculation (before falling again anyway) means it must increase by more than 300% is illogical and just incorrect.

poetryandwine · 03/08/2025 03:09

PS, when I say ‘Disagree’ I am being polite. Academics use this form to point out mistakes of fact as I have done above, as well as genuine differences of opinion.

If anyone wants to pursue a difference with me on the points I have isolated, they need to explain why @Spiderbitebatbite ’s computations rather than those usef by PPs and me model the situation correctly. Not just repeat @Spiderbitebatbite ‘s computation’s but explain why they model the situation correctly.

poetryandwine · 03/08/2025 03:00

Spiderbitebatbite · 03/08/2025 01:16

@ItsFineReally with my calculation I do not agree that the question asks you to calculate the start point and end point without also fracturing in the trebling 300% increase in between. This is why the answer must be above 300%.

200 to 600 is a 400 increase in circulation which represents a 300% increase this means the final answer must be above 300%

Next year circulation decreases by 25% so 400-100=300
300 is an increase of 150% from the starting point of 200 so

300% plus 150% is a 450% increase

The correct answer is 450%

Thanks for giving us something to work with, @Spiderbitebatbite . So, line by line;

200 to 600 is the trebling from the end of Y1 to the of Y2, an increase of 400. Agreed

But an increase of 400 is only an increase of 200% from the end of Y1 to the end of Y2. You said it was a 300% increase. (If you count from the beginning of Y1, which we all agree is wrong anyway, it is a 400% increase). Disagree here

Next year, Y3, the circulation decreases by 25%.

You use 400-100=300. I use the Y2 end figure of 600 and subtract 25%, so

600-150=450, for a Y3 end figure of 450. Disagree

So end Y1: 200. End Y3: 450.

(450-200)/200= 250/200=1.25

Amount at end of Y3 is 225% the amount at end of Y1 and the increase is 125%.

DeftShaker · 03/08/2025 02:33

You have £100 in the bank.

After 1 week, you have £300 - a nice increase!

But, the next week, you lose £75.

According to our spider friend, losing that money actually results in a bigger total increase.

DeftShaker · 03/08/2025 02:22

InWalksBarberalla · 03/08/2025 01:30

And I thought the 225% people on the other thread were bad - they've got nothing on the 450%. You can't just declare that tripling represents a 300% increase because it does not.

Somewhere right now...

Maths question - Civil Service is wrong (we now have 100% more threads about the subject)
DeftShaker · 03/08/2025 02:11

Spiderbitebatbite · 03/08/2025 00:58

@ItsFineReally That is not correct the increase in circulation from

200 to 600 is a 400 increase in circulation which represents a 300% increase this means the final answer must be above 300%

Next year circulation decreases by 25% so 400-100=300

300 is an increase of 150% from the starting point of 200 so

300% plus 150% is a 450% increase

The correct answer is 450%

Edited

😂

Thanks for doing a thread 2, OP.

InWalksBarberalla · 03/08/2025 01:30

And I thought the 225% people on the other thread were bad - they've got nothing on the 450%. You can't just declare that tripling represents a 300% increase because it does not.

miraxxx · 03/08/2025 01:27

Merryoldgoat · 03/08/2025 00:01

Honestly it’s mind boggling.

I’ve done the calculation algebraically for a third time in the hope it will help people who are still confused but I won’t hold my breath.

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You are being baited by the spider. Relax.

JuneauBound · 03/08/2025 01:26

This is fascinating to me @Spiderbitebatbite

Why are you using the circulation increase as the thing that is reduced by 25%? It should be the 600 that is reduced by 25%, no?

Separately, as has been shown, tripling is not a 300% increase.

Are you a chatbot designed to infuriate and avoid engaging with the questions people pose to help you identify the issues with your logic?

Say Potato, @Spiderbitebatbite !

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