Suppose that the amount of algae in a pond doubles every 6 hours. If the pond initially contains 50 pounds of algae, how much algae will be in the pond after 18 hours?

Question

A. 400
B. 10,800
C. 300
D. 600

Answer 1

Every 6 hours, the amount of algae doubles. Therefore, after 18 hours, the algae will have doubled three times:

First doubling: 50 x 2 = 100 pounds
Second doubling: 100 x 2 = 200 pounds
Third doubling: 200 x 2 = 400 pounds

Therefore, the answer is A. 400.