To find how long it would take him, one has to divide 400 by 160 and then multiply 5 by what that number is. You multiply 5 by the quotient because that is the number that would make it proportional. 400/160 x 5 is 12.5, meaning that the answer is 12.5 minutes, or A.
The answer to the question is C
Answer:
I think the answer is 1a : 14b
Volume (V) of a cylinder is the area of circular base (pi×r^2) times it's length/height (h):

h = 20.5 ft
diameter (d) = 1 1/5 × h, 1 1/5 = 6/5 = 1.20
d = 1.20 × 20.5 = 24.6 ft
radius (r) = 1/2 d = 24.6/2 = 12.3 ft