Question

A man in still water can swim with 13 km/h and the rate of current is 4 km/h. The distance travelled by man in downstream in 18 minutes is:

1. 8 km
2. 5.1 km
3. 4.8 km
4. 5 km
5. 6 km

Answer 1

Correct Answer - Option 2 : 5.1 km

Given:

Speed of man in still water = 13 km/hr

Speed of the stream = 4 km/hr

Time taken = 18 minutes

Formulas Used:

Speed = Distance/Time

S_(downstream) = S_(boat) + S_(stream)

Calculation:

S_(downstream) = S_(boat) + S_(stream)

⇒ S_(downstream = (13 + 4) km/hr

⇒ S_(downstream = 17 km/hr

Speed = Distance/Time

⇒ Distance = Speed x Time

⇒ Distance = 17 x (18/60)

⇒ Distance = 5.1 km

∴ The distance traveled downstream is 5.1 km

Conversion of Time from minutes to hours

1 min = (1/60) hour