Solve the problem.
-The time T necessary to make an enlargement of a photo negative varies directly as the area A of the enlargement. If 24 seconds are required to make a 3-by-4 enlargement, find the time required for a 6-by-6
Enlargement.
A) 144 sec
B) 72 sec
C) 36 sec
D) 108 sec

Question

Quizplus · Accepted Answer

The time $T$ varies directly with the area $A$, so $T = kA$ for some constant $k$. For a 3-by-4 enlargement, the area is $3 \times 4 = 12$ square units, and it takes 24 seconds. Thus, $24 = k \times 12$, so $k = 2$. For a 6-by-6 enlargement, the area is $6 \times 6 = 36$ square units. Therefore, the time required is $T = 2 \times 36 = 72$ seconds.

Solve the Problem. -The Time T Necessary to Make an Enlargement of a Enlargement