$$\begin{array} { | c | c | c | }
\hline { \text { Figure 1-1 } } \
\hline \begin{array} { c }
\text { Haurs } \
\text { Studying }
\end{array} & \begin{array} { c }
\text { Physics } \
\text { Scare }
\end{array} & \begin{array} { c }
\text { Gedlay } \
\text { Scare }
\end{array} \
\hline [ & 4 [ & 3 [ \
\hline 1 & 50 & 60 \
\hline 2 & 60 & 80 \
\hline 3 & 85 & 90 \
\hline 4 & 90 & 100 \
\hline
\end{array}$$
-Grant has four hours of time to divide between studying for a physics exam and a geology exam.Figure 1-1 shows his estimates of the grades (on a scale of 0 to 100)that he could earn from studying a particular number of hours on each subject.If he plans on spending two hours studying each subject,what would be his opportunity cost of an additional hour studying physics?
A) 10 points on his geology exam
B) 20 points on his geology exam
C) 80 points on his geology exam
D) 25 points on his physics exam
E) 85 points on his physics exam

Question

$$\begin{array} { | c | c | c | } 
\hline { \text { Figure 1-1 } } \
\hline \begin{array} { c } 
\text { Haurs } \
\text { Studying }
\end{array} & \begin{array} { c } 
\text { Physics } \
\text { Scare }
\end{array} & \begin{array} { c } 
\text { Gedlay } \
\text { Scare }
\end{array} \
\hline [ & 4 [ & 3 [ \
\hline 1 & 50 & 60 \
\hline 2 & 60 & 80 \
\hline 3 & 85 & 90 \
\hline 4 & 90 & 100 \
\hline
\end{array}$$
-Grant has four hours of time to divide between studying for a physics exam and a geology exam.Figure 1-1 shows his estimates of the grades (on a scale of 0 to 100)that he could earn from studying a particular number of hours on each subject.If he plans on spending two hours studying each subject,what would be his opportunity cost of an additional hour studying physics?
A) 10 points on his geology exam
B) 20 points on his geology exam
C) 80 points on his geology exam
D) 25 points on his physics exam
E) 85 points on his physics exam

Quizplus · Accepted Answer

If Grant spends 2 hours studying each subject, he would get a score of 60 in physics and 80 in geology. 
If he decides to spend an additional hour on studying physics, he would get a score of 90 in physics and his score in geology would drop to 50. 
Therefore, the opportunity cost of the additional hour on physics would be the difference in his scores in geology, which is 80-50=30 points. 
So, the correct answer is B, which is 20 points on his geology exam.

-Grant Has Four Hours of Time to Divide Between Studying