rito54
Hello! Silly question but how do we know that we have to divide by 24 and not 90. Could someone please explain I get confused every time with this kind of exercise not knowing which value I should divide with.
I know the formula New - Old / Old.
but how does it work here?
Help is much appreciated thank you!
When we want to know by what percentage one value is "greater than" another, we divide by the value that comes after "greater than" in the question.
This approach makes logical sense because the reference value, or "old" value, is the one that the other value is greater than.
In this case, if we were to divide by 90, then 90 would be the reference value, and we would find the percentage of 90 represented by 24, which is not what the question asks for.
Rather, we need to find the percentage by which 90 is greater than 24.
So, when calculating percentage change, always divide by the reference value. The reference value is the "old" value, or the value such that the decrease or increase is from that value.
The reference value is often named by what follows "greater than," "less than," "percent of," or "change from" in the question.