I am doing a task that it takes 2 hours. After some changes the same task takes 10 minutes. What formula I can use to calculate the improvement percentage between these 2 values?
$\endgroup$3 Answers
$\begingroup$In this case, faster is better, so the percentage of time you've removed is what you want.
Using a similar example, if you had a task that took $10$ minutes, and now can do it $7$ minutes, then you removed $(10-7)/10 = 3/10 = 30\%$ of the time. In other words, you've done the task $30\%$ faster.
Now apply this to your problem.
$\endgroup$ $\begingroup$2 hours represent 120 minutes. You've transformed 120 into 10. Let's calculate the ratio $\frac{10}{120} = \frac{1}{12}$. So you've removed $\frac{11}{12}$ of the initial value.
$\endgroup$ $\begingroup$I have a different approach. At the first time you can make $\frac1{120}$ of the task in one minute. At the second time you make $\frac1{10}$ of the task in one minute. You can interpret both figures as output per time unit (here: per minute).
Then the relative improvement is $\frac{\frac1{10}}{\frac1{120}}-1=11=1100\%$
$\endgroup$
