Question

The amount of oil used by a ship traveling at a uniform speed varies jointly with the distance and the square of the speed. the ship uses 30 barrels of oil in traveling 85 miles at 42 mi/h. how many barrels of oil are used when the ship travels 26 miles at 54 mi/h? round your answer to the nearest tenth of a barrel, if necessary.
a. 2.3 barrel

Answer 1

A = kdv^2    where A = amount oil d = distance and v = speed and k is a constant
so 
30 = k*85*42^2
Now solve for k:-
k = 30 / (85*42^2) =     0.00020008

So when d = 26 and v = 54

Amount of oil A = 0.00020008 * 26*54^2
                          =  15.2 barrels