Find average percent needed over tests to achieve a grade Simple question my mind is blanking on, but I'm trying to work out a formula for finding the average percentage score required across a number of tests given the current average. * So say there are $x$ number of tests remaining, * The student has already done $y$ number of tests of varied results, * If the student is after a final overall pass grade of 50%, what formula could be used to account for their current average and what the average percent they need on their remaining tests to achieve a pass. E.g, if the student has 7 assessment items, is after a 50% final grade , they achieved 72% on the first assessment, 44% on the second assessment, and 48% on the third assessment, what average percentage do they need from the next 4 assessments to finish with an average of 50%? Thanks.

If they need an average of $50\%$ from $7$ tests, the total of their percentages needs to be $350\%$. So far they have got $164\%$, so they need another $186\%$ from the remaining $4$ tests, which is an average of $46.5\%$.

The calculation is $$\frac{(x+y)\times\text{pass mark}-\text{total so far}}{x}.$$