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?

End of year one, numbers have doubled. But as others have said, that's a red-herring as all that matters is the number of sales at the end of year one. Anyway, based on the figures given as examples you gave at the end of year one, the end of the first year is 100.

End of the second year, sales have tripled, so they are 300 not 200.

End of the third year, they have fallen by a quarter - 25% in other words. Therefore total sales are 225.

The % difference between 100 (end of year one) and 225 (end of year three) is 125%.

I cannot for the life of me see how you got the numbers to be 100, 200, and 450.

What is a recent change? I did this over ten years ago.

The recruitment processes are blind, and part of the reason is because they pull mugs in to do the assessing (same for a lot of the normal interviews, but definitely true for the schemes) and the hundreds of people who volunteer to just do one or two days worth of assessments are not involved in some grand conspiracy of trying to weed out the intelligent ones 😂 that’s hilarious 🤣

Of course DV goes into a lot of personal detail, that’s the whole point of it ffs. What I said was that a VERY small number of fast streamers will require it, and only a small number of civil servants in general will have it. It’s expensive, and not many roles require constant access to top secret information, and SC already allows some access to top secret. So they only do it if they have to.

PLUS they have already been offered a job by the time they go through DV, so too late to weed out because they went to oxbridge and got a double first in astrophysics 🙈🤣

AND they actually ask fast streamers who wants/is willing to do DV. It’s not forced on anyone.

The CS absolutely wants intelligent people, I can promise you that! The trouble they have is retaining them….

Don’t forget though, it’s possible to be highly intelligent, but also devoid of common sense, or the ability to use soft skills that mean actually they’d not be good in the job. Those would hope the filtered out, not because of “intelligence” but for lack of capability.

50 copies is 50% so the difference of 250 copies made up of 50% added together is 450%.

My brain is fried but I can’t see another logical answer from the drop down now I’ve really looked at it.

They need to correct the wording in the question.

Better still, they need the correct answer in the answer section.

I hope you get to the bottom of it op

It reminds me of a US test where very few students said the multiple choice didn’t have the right answer as an option

250 is five 50s, so surely 250% by your logic? Which is still wrong.

450 = 9 x 50.

But you can't really add percentages like that, it depends what you're taking a percentage of. A percentage isn't an absolute, it's a relative value.

So assume you start with a base circulation of 100. That doubles after one year (end of year 1) to 200, triples after another year (end of year 2) to 600, and then reduces by a quarter to 450 at the end of year 3. The question is then looking for the increase from the end of year 1 (200) to end of year 3 (450). The increase is therefore 250 which is 125% of 200.

Use any starting number, the % change will be the same. So assume it’s 100 at the start of year 1:

Year 1 circulation doubles, so at the end of year one it's 100 x 2 = 200.

Year 2 circulation trebles so at the end of year two it's 200 x 3 = 600.

Year 3 circulation falls by a quarter, meaning it's reduced to 75% of the previous year's circulation which was 600, so reduced to 450.

To arrive at the % difference as defined in the question, calculate the difference from the end of year one to the end of year three. So: 450 - 200 = 250. Divide the 250 by the circulation at the end of year one , which was 200 = 1.25.
Multiply by 100 to get the percentage: 1.25 x 100 = 125%.

The question setter has missed a step. The answer is 125%. OP is right.

I have just texted my husband (bad at maths) who said 225.

My uni kids, one of whom is doing STEM at Oxbridge says 125. I agree with both of them.

I know it’s bonkers it’s how my brain works. After I reread the question I see it as the percentage increase in sale circulation from the base.

From the beginning base to end of year 2 350 difference so 650% (no option on drop down answer).

From end of year 1 to end of year 2 250 difference so 450% which is an option on the drop down.

As I said I got a C in GCSE maths so this is what I would have chosen 😂

Your husband has correctly told you the % you now have, based on the original.

Your kid has correctly told you the % increase.

The question asked for the % increase, therefore to answer the question correctly, only one of your family members is correct.

No my brain doesn’t compute it like that I see 250 as 5 participles (not sure if that’s the word) of 50%’s so add all the 50%’s together which makes 450%!

It is bonkers and I’m thick I know 😂

All you have to do is look at the number at the end of year one.

Then you look at the number at the end of year three.

Then you work out the % difference between the two.

He missed a stage. I have explained it to him and he now understands and agrees with me!

We also agree that the wording is awful and has been written by someone who doesn’t understand maths. We can guess the civil service wanted 225 as the answer.

This is correct. It's still based on what the original number was, not the number after it doubled, just the % increase.

I don’t know the answer. But 740 comments

This thread is like one of those annoying bodmas ones on facebook.

In language (not maths) you would say eg “a 10% increase” to mean x 110%. I would have got the correct answer without a second thought, but I can see the OP’s logic 🤷‍♀️

We also agree that the wording is awful

Genuine question, in what way is the wording awful? It clearly asks the difference between year one and year three. It's the answers which are awful.

I'd say the wording of question is clear - the problem is just with whoever calculated the options for the answers.

You wrote:
‘The % difference between 100 (end of year one) and 225 (end of year three) is 125%.’

It is not. To make it a percentage of the original (100) you have to calculate 125 (the difference) divided by the original (100) and then multiple by 100 to get the percentage increase from the original figure.

My Maths expert friend comes up with 350%. I got two different answers, neither of which are in the options. We agree that the question is badly worded and therefore ambiguous.

The OP's logic is correct - the answer is 125%, because (as you imply) a 125% increase means x 225%. What do you think the answer is?

I understand this logic based on the wording of the question however I see the wording as the percentage increase in circulation from the base using 100 in relation to the difference in end of year 1 to 2 not using the base as the number at end of year 1 only the difference from end of year 1 and end of year 2.

Maybe I’m just thick and not explaining myself well. I’m probably wrong too. I just can’t see it.

If I was answering the question I would pick 450% what would you pick given that 125% isn’t an option?

So you should! The answer is 125% The questions says from the END of the first year not the start of the first year.

225%