Boats and Streams Practice Questions

5 questions per page • Detailed step-by-step solutions

Question 6
Easy
A boat takes 10 hours to travel same distance ‘x’ upstream and downstream. If the speed of the boat is 10 km/hr and stream is 6 km/hr, then find the value of x?
A 24 km
B 28 km
C 30 km
D 32 km
Correct Answer: D

Explanation:

Upstream speed = 10 - 6 = 4 km/hr, Downstream speed = 10 + 6 = 16 km/hr. x/16 + x/4 = 10 => 5x/16 = 10 => x = 32 km.
Question 7
Easy
The distance between AB is 174 km. Two Boats Start moving towards each other at the same time at points A and B respectively. One in upstream and other in downstream. If their speed in still water is 9.6 km/ hr. and 19.4 km/ hr. respectively. Then in how much time they will meet.
A 4.5 hr
B 6 hr
C 9 hr
D 7 hr
Correct Answer: B

Explanation:

Boats move towards each other, one downstream (u1 + v) and other upstream (u2 - v). Relative speed = (u1 + v) + (u2 - v) = u1 + u2 = 9.6 + 19.4 = 29 km/hr. Time to meet = 174 / 29 = 6 hours.
Question 8
Easy
Speed of boat in still water is 12 km/hr and speed of stream is 4 km/hr. then find the time taken by boat to go 84 km and comeback?
A 11.2 hours
B 10.1 hours
C 9.9 hours
D 15.75 hours
Correct Answer: D

Explanation:

Downstream speed = 12 + 4 = 16 km/hr. Upstream speed = 12 - 4 = 8 km/hr. Total time = (84 / 16) + (84 / 8) = 5.25 + 10.5 = 15.75 hours.
Question 9
Easy
A boat cover 2 km downstream in 30 minute and cover 14 km upstream in 2 hour 20 min. find the speed of boat in still water?
A 3.3 km/hr
B 5 km/hr
C 4.3 km/hr
D 2.3 km/hr
Correct Answer: B

Explanation:

Downstream speed = 2 / (30 / 60) = 4 km/hr. Upstream speed = 14 / (2 + 20/60) = 14 / (7/3) = 6 km/hr. Boat speed in still water = (4 + 6) / 2 = 5 km/hr.
Question 10
Easy
Ratio between speed of boat in still water to speed of stream is 5:2. If 224 km is travelled by downstream in 4 hours then find the difference between speed of boat in still water and speed of stream?
A 24 km/hr
B 22 km/hr
C 28 km/hr
D 26 km/hr
Correct Answer: A

Explanation:

Boat u : Stream v = 5 : 2 => Downstream = 7x. 224 / 4 = 56 km/hr => 7x = 56 => x = 8. Difference between boat speed and stream speed = u - v = 3x = 3 * 8 = 24 km/hr.