The correct answer is 336 cubic inches.
6•8•5=240
9-5=4
4•6/2=12
12•8=96
240+96=336
out of these, it would be 4x - 4 * 2
Three million twenty nine and two hundred fifty one
The function for the height is

f(0) = 5 cos(0) + 7 = 5 + 7 = 12 (verified)
The period is T = 12 hours.
After 4 hours (t = 4), the height is

A graph of f(t) confirms the answer.
Answer: 4.5 ft