Question

If the sum of the upstream and downstream speed of a fish is 82 mph , and it travels 105 m upstream in 3hr. Find the time taken by boat to cover 126 m downstream

• A. $2.4$ hrs
• B. $2.8$ hrs
• C. $2.5$ hrs
• D. $2.68$ hrs

Answer 1

The correct option is D $2.68$ hrs

let sum of the upstream and downstream speed of a fish $=82mph.$

and distance of upstream in 3 hours $=105m$

so,speed of upstream is speed=$\frac{distance}{time}=\frac{105}{3}=35m/h$

now,speed of downstream is total distance-upstream speed =82-35

$=47mph$ time taken by boat to cover 126m downstream is=?

time=$\frac{distance}{speed}$

t=$\frac{126}{47}$

$t=2.68hrs$