Application of growth/decay

Question

The I- Touch costs $170. The value of a computer depreciates 30% per year.

a. What is the exponential decay model giving the computer's value V (in $) after t years ?

b. What is the value of the I-Touch after 2 years?

Answer 1

If it depreciates 30%, the new value is 70% of the year before.

170(0.7) after 1 year. 170(0.7)(0.7) = 170(0.7)² after the 2nd year, etc.

a .V = 170(0.7)^t

b. V = 170(0.7)²

V = $83.30