Percentage question

blamocur

blamocur

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Posted on behalf of @Headphone-7 :

Hi there,

This was the post I was trying to make to the forum:

Probably a very easy problem to solve, but I’m struggling with percentage multipliers. I know that, say, if you wanted to increase 75 by 106%, you’d multiply 75 by 1.06. But in a maths question I was given, they said that to increase a figure of around 25000 (can’t remember the exact figure) by 150%, the percentage multiplier would be 2.5. I don’t understand why this is, and it wasn’t explained.


Thanks
 
Headphone-7 said:
to increase a figure of around 25000 (can’t remember the exact figure) by 150%, the percentage multiplier would be 2.5. I don’t understand why this is, and it wasn’t explained.
Click to expand...
That would be incorrect.

150% = 150/100 = 1.5

So the multiplying factor would be 1.5 (- not 2.5).

That could be just a mis-print
 
blamocur said:
Posted on behalf of @Headphone-7 :

Hi there,

This was the post I was trying to make to the forum:

Probably a very easy problem to solve, but I’m struggling with percentage multipliers. I know that, say, if you wanted to increase 75 by 106%, you’d multiply 75 by 1.06. But in a maths question I was given, they said that to increase a figure of around 25000 (can’t remember the exact figure) by 150%, the percentage multiplier would be 2.5. I don’t understand why this is, and it wasn’t explained.


Thanks
Click to expand...
Hi @Headphone-7

Lets say you had £100 and you wanted to increase it by 150%

100% of £100 is £100 and 50% of £100 is £50 so 150% of £100 is £150. (Which is £100 × 1.5)

So to increase your £100 by 150% you would need to increase it by £150, ie: giving you £250. (£100 + £150)

And that means you would need to multiply £100 by 2.5 to get the correct result.

To take your example: 6% is a percentage fraction and it is equivalent to 0.06 as a decimal fraction.

So, as you rightly say, to increase something by 6% you can just multiply it by 1.06.

But you have to add the 0.06 to 1 to get that multiplier. The 1 preserves your original amount and the (added) 0.06 gives the (6%) increase.

The decimal equivalent of 150% would be 1.5 (150 ÷ 100). Multiplying by £100 by 1.5 would find (calculate) 150% of £100 (ie: £150) but to increase £100 by 150% you still need to add the 1 (ie: to get 2.5) to preserve your original £100 and add £150 (150% of £100) to it.

Hope that helps. 😊

NB: @Headphone-7 If you wish to add anything further to this thread just post your reply/further query in the conversation where you posted your original question. Someone will then post it in the thread for you.
 
Last edited:
Just to make it clear, this statement was incorrect:

I know that, say, if you wanted to increase 75 by 106%, you’d multiply 75 by 1.06.
Click to expand...

You multiply by 1.06 when you want to increase it by 6%, not 106%.

So a 6% increase from 75 is 75 + 0.06*75 = 75 + 4.5 = 79.5; the quick way is 1.06*75 = 79.5.
 
For further clarity, there was a typing error in Post #3

In the paragraph below, the word "by" highlighted in red was incorrectly included.
The Highlander said:
The decimal equivalent of 150% would be 1.5 (150 ÷ 100). Multiplying by £100 by 1.5 would find (calculate) 150% of £100 (ie: £150) but to increase £100 by 150% you still need to add the 1 (ie: to get 2.5) to preserve your original £100 and add £150 (150% of £100) to it.
Click to expand...

The part of the sentence should read:-

"Multiplying £100 by 1.5 would find (calculate) 150% of £100 (ie: £150)..."​

I'm afraid it was too late to edit the mistake when I noticed it (when viewing subsequent responses the following day and checking that I hadn't replicated the error mentioned by @Dr.Peterson).

Sorry for any confusion.😊
 
Can you imagine a non-math person trying to teach this topic? \
 
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