A cruise ship can sail at 27 mph in calm water. Sailing with the gulf current, the ship can sail 136 mi in the same amount of time it can sail 80 mi against the gulf current. Find the rate of the gulf current.
A) 9 mph
B) 14 mph
C) 7 mph
D) 16 mph
E) 11 mph

Question

Quizplus · Accepted Answer

Let's assume the rate of the gulf current is x mph.
When the ship is sailing with the gulf current, its effective speed is 27 + x mph.
When the ship is sailing against the gulf current, its effective speed is 27 - x mph.

We know that the ship can sail 136 mi in the same amount of time it can sail 80 mi against the gulf current. This means:

136 / (27 + x) = 80 / (27 - x)

Cross-multiplying and simplifying, we get:

3672 - 136x = 2160 + 80x
56x = 1512
x ≈ 27

Therefore, the rate of the gulf current is approximately 7 mph, which is option C.

A Cruise Ship Can Sail at 27 Mph in Calm