Question

A boat running upstream takes $8$ hours $48$ minutes to cover a certain distance, while it takes $4$ hours to cover the same distance running downstream. What is the ratio between the speed of the boat and the speed of the water current respectively?

• A. $8:3$
• B. $2:1$
• C. $3:2$
• D. $5:3$

Answer 1

The correct option is A $8:3$

Let the boat's speed while running upstream be $x$ kmph and that downstream be $y$ kmph.
Then, distance covered while running upstream in $8$ hours $48$ minutes $=$ Distance covered while running downstream in $4$ hours
$\Rightarrow x\times (8+\frac{48}{60})=y\times 4$
$\Rightarrow x\times \frac{44}{5}=y\times 4$
$\Rightarrow y=\frac{11x}{5}$
$\therefore$ Required ratio
$=\left(\frac{y+x}{2}\right):\left(\frac{y-x}{2}\right)$
$=\frac{16x}{2}\times \frac{1}{2}:\frac{6x}{2}\times \frac{1}{2}$
$=8:3$