A launch moves at 10.5 km/hr in still water. The speed of the current is 1.5 km/hr. How long will the launch take to travel 42 km downstream?
Answer & explanation
Correct answer: option 1
The correct answer is Option (1) → 3 hours 30 minutes
Downstream the current is added to the launch’s own speed.
Downstream speed \(=10.5+1.5=12\) km/hr
Time \(\displaystyle =\frac{42}{12}=3.5\) hours
\(0.5\) hour \(=30\) minutes, so the time is 3 hours 30 minutes