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're working for the government here so although the answer should be 125% that option is hidden and the more favourable 225% increase put out as fact. It's a true test of 'are you suitable for the civil service?'

Given the answer is clearly 125% the question for me is whether the actual test is of the gumption of the candidate to point out the mistake.

The AIBU poll results so far are a cause for concern 😬

Horsie brought so much joy to this thread. The meditation on how 1 x 1 is 1 was particularly inspired.

The post saying that to increase something by 100% you multiply it by 1 is unbelievably stupid

Multiplying something by 1 makes it increase by 0%.

Even on the reasoning you were following, the math is wrong.

When most of us start from 100 newspapers, we end up trying to calculate 450 as a percentage increase on 200.

You are calculating 100 as a percentage of 225, which is equivalent.

In your understanding of the facts, the question you are answering is "how many newspapers were sold in year 3?", which is not what is being asked.

Caveat: I very much doubt this was done deliberately. However I think seeing how someone deals with this situation would actually be a good indicator how good they are to work with.

All the proposed answers are objectively incorrect.

Does the candidate notice?
Do they let it go?
Do they point out the error, and how do they go about that?
Are they triumphantly announcing that everyone else is stupid an they are right?
Do they alert people that there is an error but go about it in a constructive way?
Are they able to clearly explain their reasoning and take others along with them?

You are correct OP. Have voted to confirm! Shame on who set the question.

It would be an interesting group question when the group had to present the answer.

This is a really common error with percentages and what words we use around them. It boils down to the difference between:

1. 'express the total value at the end of year 3 as a percentage of the value at the end of year one' (which is where people get 450/200= 225%) and
2. 'express the difference between the end of year one to the end of year three as a percentage of the value at the end of year one (which is where people get (450-200)/200=125%)

@Jacopo how can I change my vote? I didn’t know that was possible!

(not on this thread, the OP is NBU and I didn’t think she was. But sometimes I press the wrong one by mistake or change my mind and regret my vote!)

Horsie was great when she finally got it. . I am fascinated by this thread, more by the psychology of the posters than anything else and have seen only 3 posters acknowledging their mistake.

Just click the correct one.

I think you should tell the recruiters that there's an error in the test. You're definitely correct and it's embarrassing for them to have an error in the test. I can't think you would be penalised for pointing the error out, I think it would be a positive to employ someone who can spot errors and will speak up when they see them. But if you're worried you could wait until you hear the outcome of your application. Either way I would tell them though, they really need to correct the error!

Good luck with your application!

The irony 😅 I hope that percentage will be correct

Also OP to answer the question as a civil servant, pointing out the error will neither go in your favour or against you, the whole point of the civil service entry is that it is fair and open so decision makers and the HR sorting out test results will be separate. However I would finish the test and tick 225% just to get it done and know you didn’t lose any marks.

I think 125% is correct as well. I have multiple maths degrees if that has any bearing on my answer but maybe it doesn't 😂

If a box of cereal normally has 100g and a new box is 150g you'd say it was 50% more, 50% bigger than the original. A 50% increase. 50% of the original has been added on.

You are going from 200 to 450 so 250 has been added on, which is 125% of 200. It is 125% bigger than it was 2 years ago.

For the people saying it's 225%, you need to remember that if something increases by 100%, that does not mean it has stayed the same.

Just click on the other option and your vote will change (unless voting has closed).

As a physics PhD, OP is absolutely correct because it’s asking for the percentage increase from the end of year 1 to the end of year 3.

As a civil servant, please do point this out to the recruitment team. It could very well have been a typo but if not, it’s a very badly worded question. They will appreciate it, certainly won’t put you at a disadvantage.

This makes no sense whatsoever, percentage is the unit, increase is what you’re doing to it (similar to an ‘operation’ in maths).

If percentage means percentage increase, what’s the term for percentage decrease?

Numbers can be confusing. I said this was a primary school level question in Singapore. Here is how an 11 year old would be taught the question diagrammatically. They start with a unit (purple). Maths taught this way is very effective, imo.

OP, you are really not cut out for the civil service as you are logically questioning things and thinking for yourself in a sane way.

Best of luck!

You are correct OP, as they are asking for percentage increase not percentage of the original value.

Say you have £200. You still have £200. You have had 0% increase, but 100% of the original value.

Then that £200 becomes £450. You have 125% increase, and 225% of the original value.

And on a side note... another time, you have £100. It decreases by 75% to £25; you have 25% of the original value.

I agree its 125%. I teach maths. Some of the people on this thread need to retake their GCSE maths judging by their answers!!