Solve word problems involving trigonometric models (Question 2)

A Cepheid variable star is a star whose brightness alternately increases and decreases. Suppose that the interval between times of maximum brightness for a particular star is 7.3 days, its average brightness is 5.0, and that it changes by ±0.2.

(a) Formulate a model of the form y=a(sin⁡〖(bx))+d.〗

(b) If the brightness today is 5.0, how long will it take until the star reaches its maximum brightness?