# Percentage difference problem

tahmidbro
Homework Statement:
My answer does not match with the ones in book
Relevant Equations:
N/A

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Homework Helper
If you read the question, you will find that you were asked to compare against 1.1, not against 1.2
the poorly quoted question said:

tahmidbro
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Homework Statement:: My answer does not match with the ones in book
Relevant Equations:: N/A

See the question : https://www.thestudentroom.co.uk/att...hmentid=978958

I have got the answer to the vertical height gained = 1.355 m. No problem.

But not the value of the percentage difference. Their value : 23%, my value =( (1.355-1.2 )/1.35) x 100% = 11.48%

Well, I suspect that they are multiplying %D by 2, but why?
You are asked for the % difference relative to 1.1m, so you should divide (1.355 - 1.1) by 1.1

tahmidbro
Now I understand. Thank you!

Homework Helper
I have a minor quibble with the response given by @Steve4Physics. He points out quite correctly that if one is computing the percentage difference of 1.355 from 1.1 that one should divide the delta by 1.1.

However, the question at hand does not specify whether we should use the 1.1 or the 1.355 as the baseline.

the poorly quoted question said:
calculate the percentage difference between the two answers
There is nothing in that request that elevates either of the two answers to the status of baseline. One could argue for the correctness of any of three possible answers to this ambiguous question.

1. ##\frac{\text{high}-\text{low}}{\text{low}}##
2. ##\frac{\text{low}-\text{high}}{\text{high}}##
3. ##\frac{\text{high}-\text{low}}{\text{high}}##

tahmidbro
Sorry for forgetting to upload the 'worked example' along with the question

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Homework Helper
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There is nothing in that request that elevates either of the two answers to the status of baseline. One could argue for the correctness of any of three possible answers to this ambiguous question.
Agreed that the question isn't particularly well expressed, but the OP's first link explicitly says