Answer:
20% psyche test scores
Step-by-step explanation:
Given that every week, Bob plays the guitar for three hours, and his grade on each psych test is 75 percent.
Last week, after playing for three hours, Bob considered playing for an additional hour.
He decided to play for another hour and cut his study time by one hour, but last week his psych grade was 55 percent.
Bob's opportunity cost of the fourth hour of playing the guitar
=His cut in scores in psyche test
=20%
