Question

If the time taken by boat to go 28 km downstream and 30 km upstream is 2.5 h. If the ratio of the downstream and upstream speed is 7:5, then find the speed of the boat in still water, ​

Answer 1

Answer:

The answer is 24 km/hr.

Step-by-step explanation:

Given: Downstream distance = 28 km

           Upstream distance = 30 km

Total time taken = 2.5 hr

The ratio of the downstream and upstream speed = 7 : 5 = 7x : 5x

$\frac{28}{7x}$ + $\frac{30}{5x}$ = 2.5 hr

140 + 210 ÷ 35x = 2.5 hr

$\frac{10}{x}$ = 2.5

x = 4

Speed of the boat = 7x + 5x ÷ 2 = 6x

6 × 4 = 24 $\frac{km}{hr}$