Maths test - to think Civil Service have it wrong?

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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?

I refer you to @horsie ‘s post, which says:

Because increasing 200 by 125% isn't 450. Increasing 200 by 125% is 250.
1 x 200 = 200
25% of 200 is 50.
125% of 200 is 250

This is the increase expressed as a percentage. It is not what happens if you add 225% but that’s not what increase by a percentage means - see my post with steps

No, it is not. It’s 125%.

You are right that 225% of 200 is 450. But we are being asked to calculate the increase. If something doubles in price, e.g. from £200 to £400, the price has increased by 100%, not 200%. As you say (only applying it wrongly) it’s simple percentages.

OP is correct - the sales increased by 125%.

I would like to ask the 225% brigade how they would increase a number by 225%

To increase a number by 100%, you would multiply by 2

e.g. 200 * 2 = 400. A 100% increase

Your math isn't wrong if you are trying to express year 3 end as a percentage of year 1 end. But the question doesn't ask for that. It asks for the INCREASE in circulation. So you need to take the year one end total out of the year 3 end total to calculate the increase before calculating the percentage.

Which means you've missed out a step d.2) 2.25x - x (year 3 end - year 1 end, i.e. the increase in circulation) which is 1.25x

then steps g-h become:
(g) we can now use our equation to get an answer - which is 1.25 * 100% which
(h) = 125%

Because increasing 200 by 125% isn't 450. Increasing 200 by 125% is 250**

No, this is wrong.

Increasingly 200 by 100% is 400, not 200.

If you had 200 Haribo eggs and someone said they’d give you 100% more, you’d end up with 400, wouldn't you?

If you were earning £200 a day and your boss said he was giving you a 100% increase, your wage would go up to £400 a day, wouldn’t it? Or if he offered a 10% increase, you’d be up to £220 a day.

Is it not a bog standard percentage change? So (450-200)/200 x100 =125%

This post is incredible. The extent people go to to try to prove they are right, some with some fairly complex maths, but fundamentally miss a basic point.

#Team125%

So you think that 450 is 225% more than 200?
See - I think that 400 is 100% more than 200 and that 600 is 200% more than 200

Can you correct my maths

I want to increase 200 by 100% so I add on 200 to get 400.

I add on another 200 to get 600. So 600 is 200% more than 200.

So how can 450 be 225% more than 200

It’s confirmation bias, because the original question is wrong

It's ridiculous if it means the resulting answer doesn't actually show an increase.

If you multiply a(ny) number by 100% it stays the same. How could that possibly be what's meant by "percentage increase"?

And if you multiply a number by <100% it decreases. How could that possibly be a "percentage increase"?

The Civil Service may not be looking for geniuses but I'm sure they'd prefer to recruit someone who knows what the word "increase" means.

I love how you've typed all this out but got it so wrong.
If a client asks you to increase the length of your design by 100% do you send it back unchanged?

Agree — I have A-level maths, but I was taught percentages vs percentage increases in upper primary school, not at GCSE or A-level! (In fact by A-level you wouldn’t really ever be using percentages, only algebraic fractions.)

The basic problem here is that posters are failing to recognise the difference between percentages and percentage increase. They are not the same thing. A bit like mistaking turnover for profit, IYSWIM.

Increasing your salary by 25% must be terrible then.

Shhh, let the 225% brigade have their fun with pages of useless calculations.

Almost no one thinks the maths is hard. About half of people aren't familiar with the term percentage increase, or found the wording ambiguous.
Yes 450 is 200 increased by 125% of its value.
But 450 is also 200 increased to 225% of its value.

200 x 225% is the same as

200 x225/100 =450
So 200 to 450 is a x225% increase.

Although I can totally see why it would be 125% as well😳

You win 🤣

OP，you are right. The question setter is confused about "increase"

100%. ->120% 20% increase

And the arguments in this thread reflect the OECD survey: "
• UK adults have lower numeracy skills than the OECD average.
• A significant portion of the population struggles with basic math, like percentages etc."

Now you’re talking my language (I’m an accountant and if I couldn’t calculate a percentage increase properly I shouldn’t have a job).

I would have answered 225%

🤣👌🏾

No
'
It is not a 225% increase

If your pay went up by 100%, what would be the easiest way to work it out?

You would multiply it by 2

If inflation was 100%, then the cost of goods would be twice as much

Indeed. This is a test of comprehension as much as maths. In fact the maths is trivial once comprehension is achieved.

OP - I think the many posters on this thread who think it's 225% are showing just how poor numeracy is in the UK and may give you an inkling of why the test is wrong in the first place (or it might just be it's an easy miss that it's asking for the increase rather than an expression of y3 end as a percentage of y1 end).

I would have have checked 225% but hand noted why the answer was incorrect and that it should be 125%. If they mark you down for that it's going to be a nightmare of a place to work.