Description for Correct answer:
The leak admits water at the rate of 3 tonnes every 10 minutes = \( \Large 3 \times 6 \)

= 18 tonnes every hour.

The pumps throw out water at the rate of 3 tonnes every hour.

Therefore, net water that gets into the ship = 18 - 3 = 15 tonnes every hour. '

45 tonnes of water will sink the ship.

Therefore, the ship has got \( \Large \frac{45}{15} \) = 3 hours before it will sink.

The port is 75 kms away. Hence the ship should cover 75 kms in 3 hours i.e at the rate of 25 km/hr.