The original size of the creature was 100 cubic feet. The creature doubles in size everyday for 5 days. How big was the creature on the fifth day?

Question

Write a general formula for the solution to this problem.

Answer 1

For a geometric sequence:

 

a_n = a₁(r)^n-1

a₅ = 100(2)^5-1

a₅ = 100(2)⁴

a₅ = 100(16)

a₅ = 1600

 

Or

 

100, 200, 400, 800, 1600.