The speed of a boat in still water is 10 km/h. The speed of the stream is 2 km/h. What is the total distance that the boat will travel if it is rowed for 4 hours upstream and 3 hours downstream?

68 km

We know that,

Upstream Speed = Speed of Boat – Speed of current

Downstream Speed = Speed of Boat + Speed of current

Given,

The speed of the boat = 10 km/h

The speed of the stream = 2 km/h

Upstream speed = 10 – 2 = 8 km/h

Downstream speed = 10 + 2 = 12 km/h

According to the question,

the total distance that the boat will travel if it is rowed for 4 hours upstream and 3 hours downstream = 8 × 4 + 3 × 12  = 32 + 36 = 68Km