Target Exam

CUET

Subject

General Test

Chapter

Numerical Ability

Topic

Boats and Streams

Question:

The time taken by a boat to travel 13 km downstream is the same as time taken by it to travel 7 km upstream. If the speed of the stream is 3 km/h, then how much time (in hours) will it take to travel a distance of 44.8 km in still water?

Options:

$4 \frac{12}{25}$

$5 \frac{3}{5}$

$5 \frac{2}{5}$

$4 \frac{13}{25}$

Correct Answer:

$4 \frac{12}{25}$

Explanation:

Speed of the stream = 3 km/hr

Let speed of the boat be y km/hr

Time =  \(\frac{ Distance }{ Speed }\)

According to the question

\(\frac{ 13}{ (y + 3) }\) = \(\frac{ 7}{ (y - 3) }\)

= 13 (y – 3) = 7 (y + 3)

= 13y – 39 = 7y + 21

= 13y – 7y = 21 + 39

= 6y = 60

= y = 10

So, speed of boat = 10 km/hr

Time taken to cover 44.8 km distance in still water = \(\frac{ 44.8}{ (10) }\) = $4 \frac{12}{25}$