Question

Together two ferries can transport a day's cargo in 7 hours. The larger ferry can transport cargo three times faster than the smaller ferry. How long does it take the larger ferry to transport a day's cargo working alone?

Answer 1

It takes the larger ferry 9 hours and 20 minutes to work alone.

Explanation:

If the two ferries work together and transport a day's cargo in 7 hours

And if the larger ferry can transport cargo three times faster than the smaller ferry,

This implies that the speed ratio of the larger ferry to the smaller ferry is equal to 3 : 1

Then the sum of the ratio = 4 (3 + 1)

From the above, it will take the smaller ferry 28 hours to work alone (7 x 4), given its speed proportion of 1: 3.

Therefore, when the larger ferry works alone, it will take it (7 x 4)/3 = 9.33 hours.

9.33 hours = 9 hours, 20 minutes.