Correct Answer - Option 4 : 40 hours

**Given**

Total distance in each case = 558 km

Speed of boat = 40 km/h

Speed of current = 22 km/h

**Formula used**

Time = Distance/Speed

Downstream speed = (Speed of boat + Speed of current)

Upstream speed = (Speed of boat - Speed of current)

**Calculation**

Time in downstream = (558)/(40 + 22) = 558/62

⇒ Time in downstream = 9 hours

Time in upstream = 558/(40 - 22) = 558/18

⇒ Time in upstream = 31 hours

Total time = 9 + 31

⇒ 40 hours

**∴ Time taken by boat to travel upstream and downstream is 40 hours.**