1- A company's marginal cost function isMC=15x^3/220x^2/3+ 1, wherexis the number of units, and fixed costs are$7000. Find the cost function, c(x).

C(x)=?

2- An airline finds that if it prices a cross-country ticket at$200, it will sell 300 tickets per day. It estimates that each $10 price reduction will result in 50 more tickets sold per day. Find the ticket price (and the number of tickets sold) that will maximize the airline's revenue.

ticket price$??

number of tickets???

3- An investment grows at 24% compounded monthly. How many years will it take to do the following? (Round your answers to one decimal place.)

(a)triple

???yr

(b) increase by25%

???? yr