Answer:
48
Step-by-step explanation:
Let the scores be a,b,c,d,e,f.
So sum of these scores = mean * 6
= 78 X 6
After say removing test score a, mean = 84 %
So sum of these remaining scores = mean * 5
= 84 X 5
Having calculated these two, the removed score = difference of the two sums.
So removed test score = 78 X 6 - 84 X 5
= 48