Word problem using sines - Please help!

[Cori]

I have no idea how to do this problem can someone please help me!

The depth of water in a tank oscillates sinusoidally once every six hours. The smallest depth is 5.5 ft and the largest is 8.5 ft.

a) Find a possible formula for the depth of water in tank in terms of time if at the time, the depth is 7.5 ft.

b) For how many minutes (rounded to two decimal places) during one period is the depth of water in the tank at least 7.5 ft?

 

[stapel]

From the minimum and maximum depths, what amplitude did you get? About what base-value does this sine curve oscillate?

If the period is six hours, then what is the argument of the sine?

Eliz.

 

[Cori]

I don't know. This is a confusing problem, I'm not sure how to set it up to solve it. All I know is that you use sine or cosine, but I'm lost with this problem