A mathematics textbook author has determined that her monthly gas usage y approximately follows the sine curve

where y is measured in thousands of cubic feet (MCF) and t is the month of the year ranging from 1 to 12.
(a) Graph this function on a graphing calculator.
(b) Find the approximate gas usage for the months of February and July.
(c) Find dy/dt, when t = 7. Interpret your answer.
(d) Estimate the total gas usage for the year.

Transcribed Image Text:

y = 12.5 sin (t (t + 1.2)). + 1.2)) + 14.7,