Question

If time taken to cover(D+11)km upstream is thrice the time taken to cover (D-3)km downstream. If ratio of speed of boat in upstream to downstream is 3:7 and time taken to cover (D+18)km downstream is 2.5 hours, what will be the speed of current?

Answer 1

Sorry I didn't know the answer so I hope you don't mind it.

Answer 2

Answer:

Speed of current is 8 km/hr

Step-by-step explanation:

Distance of upstream = D+11

Distance of Downstream = D-3

The ratio of speed of boat in upstream to downstream is 3:7

Let the ratio be x

So, Upstream speed = 3 x

Downstream speed = 7x

So,$Time= \frac{Distance}{Speed}$

We are given that  time taken to cover(D+11)km upstream is thrice the time taken to cover (D-3)km downstream.

So, $\frac{D+11}{3x}=3(\frac{D-3}{7x})$

$D=52$

We are given that Time taken to cover (D+18)km downstream is 2.5 hours,

So, $7x=\frac{D+18}{2.5}\\7x=\frac{52+18}{2.5}\\x=4$

So, Speed of current = 2x = 2*4 = 8 km/hr

Hence Speed of current is 8 km/hr