Question

The value, V, of a $25000 vehicle after y years is given by V = 25000 (0.85)y

What is the rate of depreciation? (1 mark)
What will the car be worth after 5 years? (1 mark)
To the nearest month, how long would it take to reduce the vehicle’s value to 10% of its original amount? (3 marks)

Answer 1

you probably meant

V = 25000 (.85)^y

a) replace y with 5
V = 25000(.85)^5
= ....

b) when is it worth 2500 ?
(.85)^y = .10
log both sides
log (.85^t) = log .10
t log .85 = log .10
t = log .10/log .85 = 14.168 years
or 14 years and 2 months