A boat running downstream covers a distance of $16 \mathrm{~km}$ in 2 hours while for covering the same…
A boat running downstream covers a distance of $16 \mathrm{~km}$ in 2 hours while for covering the same distance upstream, it takes 4 hours. What is the speed of the boat in still water?
$4 \mathrm{~km} / \mathrm{hr}$
$6 \mathrm{~km} / \mathrm{hr}$
$8 \mathrm{~km} / \mathrm{hr}$
Data inadequate
Solution
Rate downstream $=\left(\frac{16}{2}\right) \mathrm{kmph}=8 \mathrm{kmph} ;$ Rate upstream $\left(\frac{16}{4}\right) \mathrm{kmph}=4 \mathrm{kmph}$. $\therefore$ Speed in still water $=\frac{1}{2}(8+4) \mathrm{kmph}=6 \mathrm{kmph}$