Answer:
C
Step-by-step explanation:
Represent what you have to be more specific
100,000
because the 8 makes the 9 round up into a 10
You should be able to multiply 91 by 8 to get the sum of the first 8 tests, then add the score on the 9th test. Then to get the average of the sum of the 9 tests you need to divide it by 9.
((91*8)+78)/9=89.555555555555.... So, 90%
