We have the following possible function
h = A sin (Bt - C) + D
A = the amplitude = 50/ 2 = 25
D = the shift upward = 25 + 6 = 31
C = the phase shift = pi/2
B = the number of periods in 2 pi = 2pi/10 = pi/5
So....the function is
h = 25 sin (( pi / 5) t - pi / 2) + 31
b) at 12 minutes the height is 25 sin ( (pi/5) (12) - pi/2) + 31 =
25 sin [ (12/5) pi - (1/2) pi ] + 31 =
25 sin [ 1.9 pi ] + 31 ≈ 23.27 m
c) See the graph here : https://www.desmos.com/calculator/i5cl7732ha
The ride will be at 46 m at about 3.5 min
d ) See the graph here : https://www.desmos.com/calculator/kxrxtlnhsq
The ride will be above 10m from about .913 min ( ≈ 54 sec) to about 9 min