The sum of his previous grades were 308. In order to get an average grade of 78, he needs to have a score of 78*5 or 390. His necessary grade minus his current grade is 390 - 308, which is 82. The minimum score the student needs to get on his test in order to have an average of 78 is 82
Step-by-steYou can make a new table to add the amounts and copy the pre-existing amounts or just add a new bar, but I guess it will be better if you just do it again.
