Answer:
83.85%
41%
Step-by-step explanation:
a) We assume the best grade that can be earned on the final is 100%. Then the best course grade is ...
(0.85)(81%) +(0.15)(100%) = 68.85% +15% = 83.85%
__
b) For a course score of 75%, we need a final score such that ...
(0.85)81%) +(0.15)f = 75%
68.85% +0.15f = 75% . . . simplify a bit
0.15f = 6.15% . . . . . . subtract 68.85%
f = 41% . . . . . . . . divide by 0.15
The minimum final exam score for a course grade of 75% is 41%.
