A maths question!

[DucksInARowingBoat]

If something costs £572 and inflation is 4.2% what will it cost next year?

I have my answer but I want to see what you come up with as it keeps telling me Im wrong.

Just to add, the instructions say to work out the result you should multiply the current price by the percentage increase. However I work that out to be 320% increase.

When multiplying by a percentage, 100% is equivalent to 1 - because 100% of something is the same as multiplying it by 1!

So if 100% is 1
10% is 0.1
1% is 0.01

So 4.2% is 0.042

So to get 4.2% of any number you have to multiply that number by 0.042

To get a 4.2% increase, that is the same as saying 104.2% of the original number. So you can instead multiply the original number by 1.042.

I don't understand why the course is wrong? You can indeed work out the price increase by multiplying the current price by the expected inflation rate. It's just that the question doesn't ask you to work out the price increase, but rather the new price. Doesn't make what they said before wrong.

The question is worded confusingly.

"You can estimate the price inctease of an item by multiplying it's current price by the expected inflation rate"
To get the increase you multiply the original price by the decimal equivalent of 4.2%. So £572 x 0.042=£24.
But you could easily read that as telling you to multiply by 4.2.

The question is "the item costs £572.00. If it's cost increases at the rate of inflation of 4.2%, what will it cost next year?".
This is not asking for the increase. It's asking for the total cost. So £572+£24=£596.
You have to add the increase to the original cost.

As others have said to do this in a single step you do 572 x 1.042.

The 1 gives you the 572 and the .042 gives you the 24.

If you use 0 ie 572 x 0,042 then it gives you the rise ie 24.024. If you put the 1 in ie 572 x 1.042 then it keeps the 572 in (1 x 572 = 572) and adds on the rise so you get the correct answer (596.024) rather than just how much it would rise by.

Or you can just Google '4.2% of 572' and it tells you that it's 24.024, then just add it on.

I dont think so. I think it's 320% increase?

4.2 x 572 = 2402
2402 - 572 = 1802
1802 / 572 = 3.2
3.2 x 100 = 320

Not that it matters because that is wrong anyway. 😆

How on earth does someone with an a* in maths not understand percentages?

Yes. The new price is £596 but the course is saying it isnt.

OK word it differently.

If you multiply by 4.2, that gives you 420% of 572. Which yes is a 320% increase.

As usual it's a crap question that omits relevant detail.

The inflation rate isn't qualified. Is that per month or per year ?

Making another assumption, that the something costs £572 now (which isn't stated), exactly when next year are you trying to find out the cost ?

Reading OP’s posts, it sounded like

“You can estimate the price inctease…” is the actual wording of the question

and her OP “what is price next year” was paraphrasing and in the process asking a different question.

Yes.

We all agree that £596 is the answer but the course is saying it isnt.

I put in 24 as well in case they meant the increase but that was wrong too.

It's a basic course so I think we can asume it's 4.2 for the whole year.

i am getting confused!
I will revert to my previous post and ask - do they want to know price rise (I.e difference in price between the two years) or the actual new price next year?

ETA perhaps they want £24.02 as the answer?

That makes sense. Thank you.

🤣 I have typed the wording exactly.

I'll try and remembet to let you know what they say the answer is.

Nope. Tried that when 596 didnt work.

I've tried with and without £ sign and pennies and rounding up and rounding down.

Tis a mystery.

Sorry I still don't understand- what is the course saying the answer is?

So far as I can tell the course is saying that to calculate the increase of the thing that costs £572 now you do £572 x 0.042, I.e.multiply the price now by the expected inflation rate. That's completely correct.

It then asks the question of what the new price will be, in which case you do £572 x 1.042, which is the same thing as adding the increase to the original price.

So where is the course wrong?

This is a beautifully clear explanation.

572 is your starting point, your "whole", your "1", your 100%.
Getting your head round the idea that 100%=1 is the crucial point.

Have you tried £596.02 rather than £596? Or 24.02?

Do update us when you find out the answer @DucksInARowingBoat !

I have emailed them to see what they say.

It doesnt say. If it did tell me what they thought the answer was I could work backwards.

Anyway, everyone got the same answer as me whoch is why Ive decided the ourse is wrong. 🤣

Sorry I misunderstood earlier, you are absolutely correct that if it's not accepting £596.02 as the answer then it is indeed wrong!

The course isn't wrong.

You CAN estimate the INCREASE by multiplying the cost by the INFLATION RATE which is 4.2% aka 0.042 times the original price.

It is asking you to add that to the original price and give the answer which is them both added together. AKA 1.042 times that original price.

Nothing gets times by 4.2 at all.

The course is wrong because it isn't accepting what we all agree to be the right answer.