Thread: rates and related rates

An item costs $600 at time t = 0 and costs $P in year t. When inflation is r% per year, the price is given by the following equation.
P = 600e^(rt/100)
(a) If r is a constant, at what rate is the price rising (in dollars per year) initially?

At what rate is the price rising after 2 years?

(b) Now suppose that r is increasing by 0.3 per year when r = 4 and t = 2. At what rate (dollars per year) is the price increasing at that time?

i would appreciate some quick help here please...thanks

Originally Posted by mathaction

An item costs $600 at time t = 0 and costs $P in year t. When inflation is r% per year, the price is given by the following equation.
P = 600e^(rt/100)
(a) If r is a constant, at what rate is the price rising (in dollars per year) initially?

At what rate is the price rising after 2 years?

First for constant we need:



Then when we have the initial rate of increas in price is:



After 2 years we have:



RonL

Originally Posted by mathaction

An item costs $600 at time t = 0 and costs $P in year t. When inflation is r% per year, the price is given by the following equation.
P = 600e^(rt/100)
(a) If r is a constant, at what rate is the price rising (in dollars per year) initially?

At what rate is the price rising after 2 years?

(b) Now suppose that r is increasing by 0.3 per year when r = 4 and t = 2. At what rate (dollars per year) is the price increasing at that time?

i would appreciate some quick help here please...thanks

For non-constant we have:



Now just insert the values to get the answer.

RonL