Question

The ratio of the speed of boat in still water to the speed of stream is 16:5. A boat goes 16.5 km in 45 minute upstream, find the time taken by boat to cover the distance of
17.5 km downstream.​

Answer 1

Answer:

The time taken by boat to cover the distance of

17.5 km ddownstream is 25 minutes.

Solution:

Let the speed of boat in still water = 16x, speed of stream = 5xUpstream speed = 16x – 5x = 11x

$s = \frac{d}{t} \\ 11x = \frac{16.5}{45} \times 60 \\ x = 2$

speed of boat in still water = 32 km/h, speed of stream = 10 km/h

Downstream speed = 32 + 10 = 42 km/h

Distance = 17.5 km

$time = \frac{17.5}{42} \\ = \frac{5}{12} \: hours \\ or \frac{5}{12} \times 60 = 25 \: minutes$

Answer 2

Answer:

this answer is in detailed

Step-by-step explanation:

from first condition,

Speed of boat in still water : Speed of stream = 16 : 5

let common multiple be x

then,

Speed of boat in still water = 16x km/min

Speed of stream = 5x km /min

speed of boat in upstream = 16x - 5x

= 11x km/min

speed of boat in downstream = 16x + 5x

= 21x km/min

we have,

speed = distance/time

from second condition,

11x = 16.5/45

x =1/30

we have,

speed = distance/time

time = distance/speed

time taken by boat in upstream = 17.5/21x

= 17.5/21/30

= 17.5 × 30/21

= 25 min