Speed of a boat in still water is 5times more than the speed of stream. If boat covers 72 km in downstream in 6 hours, then find the time taken by the boat to cover 88 km in upstream.
Let the speed of stream be ‘x’ km/hr. So, speed of boat in still water = 5 × x = 5x km/hr Downstream speed of boat = 5x + x = 6x km/hr According to question; 6x = 72/6 = 12 Or, x = 2 Upstream speed of the boat = 5x – x = 4x = 4 × 2 = 8 km/hr Required time taken = 88/8 = 11 hours
