The current cost of a hamburger is $4, but it is increasing by 9% every year.

Question

a. Write the exponential function that models this situation.

b. How much will the hamburger cost in 2 years?

c. How much will it cost in 4 years and 6 months from now?

Answer 1

a.  4(1.09)^n  price of hamburger at n year.

b.  cost of hamburger after 2 years = 4(1.09)^2 = $4.75 approx

c. since increasement takes place every year (at the begining of the year )and lasts for the whole year

if we calculate the price 4 years from now,  the price will be the same for the next 6 months.

so price for 4 years and 6 months from now;  4(1.09)^4 = $5.65 approx