Answer: The correct answer is "$3"
Explanation:
Output Average Fixed Cost Average Variable Cost
1 $50.00 $100.00
2 25.00 80.00
3 16.67 66.67
4 12.50 65.00
5 10.00 68.00
6 8.37 73.33
7 7.14 80.00
8 6.25 87.50
The marginal cost of the fifth unit of output is $68 - $65 = $3.