Question 1

1. The ratio of the speed of a boat in still water to the speed of the stream is 8 : 1. If the boat travels 36 km downstream in 2 hours, find the speed of the stream.

A) 1 km/hB) 2 km/hC) 3 km/hD) 4 km/h

Answer

✓ Correct Answer: Option B

Explanation: Solution: Downstream speed $D = \frac{36}{2} = 18$ km/h. Let speed of boat be 8x and stream be x. D = 8x + x = 9x. 9x = 18 ⇒ x = 2. Speed of stream = 2 km/h.

Question 2

2. A boat covers 24 km upstream and 28 km downstream in 6 hours. It covers 30 km upstream and 21 km downstream in 6.5 hours. The speed of the stream is:

A) 2 km/hB) 3 km/h 4 km/h

Question 3

3. A man can row 6 km/h in still water. If the speed of the current is 2 km/h, it takes him 3 hours more to go upstream than downstream for the same distance. The distance is:

A) 24 kmB) 30 kmC) 18 kmD) 32 km

Answer

✓ Correct Answer: Option A

Explanation: Solution: Boat speed B = 6, Current C = 2. Downstream D = 8, Upstream U = 4. Let distance be x. $\frac{x}{4} - \frac{x}{8} = 3$. $\frac{2x - x}{8} = 3 ⇒ \frac{x}{8} = 3 ⇒ x = 24$ km.

Question 4

4. A boatman goes 2 km against the current of the stream in 1 hour and goes 1 km along the current in 10 minutes. How long will it take him to go 5 km in stationary water?

A) 40 minutesB) 1 hourC) 1 hour 30 minsD) 1 hour 15 mins

Answer

✓ Correct Answer: Option D

Explanation: Solution: Upstream speed U = 2 km/h. Downstream speed $D = \frac{1}{10/60} = 6$ km/h. Speed in still water $B = \frac{6+2}{2} = 4$ km/h. Time to cover 5 km = $\frac{5}{4}$ = 1.25 hours = 1 hour 15 minutes.

Question 5

5. The speed of a boat in still water is 15 km/h and the speed of the current is 3 km/h. The distance travelled downstream in 12 minutes is:

A) 2.4 kmB) 1.8 kmC) 3.6 kmD) 4.2 km

Answer

✓ Correct Answer: Option C

Explanation: Solution: Downstream speed D = 15 + 3 = 18 km/h. Time = 12 mins = $\frac{12}{60}$ = 0.2 hours. Distance = $18 \times 0.2 = 3.6$ km.

Question 6

6. A boat takes half the time to move a certain distance downstream than upstream. What is the ratio between the speed of the boat in still water and the speed of the current?

A) 2 : 1B) 3 : 1C) 4 : 3D) 5 : 2

Answer

✓ Correct Answer: Option B

Explanation: Solution: Let D be downstream speed and U be upstream speed. Time downstream = $\frac{1}{2}$ Time upstream ⇒ D = 2U. B + C = 2(B - C) ⇒ B + C = 2B - 2C. B = 3C ⇒ B:C = 3:1.

Question 7

7. A man rows to a place 48 km distant and back in 14 hours. He finds that he can row 4 km with the stream in the same time as 3 km against the stream. The rate of the stream is:

A) 1 km/hB) 1.5 km/hC) 2 km/hD) 2.5 km/h

Answer

✓ Correct Answer: Option A

Explanation: Solution: Ratio of Downstream speed to Upstream speed = 4 : 3. Let D = 4x and U = 3x. $\frac{48}{4x} + \frac{48}{3x} = 14 ⇒ \frac{12}{x} + \frac{16}{x} = 14$. $\frac{28}{x} = 14 ⇒ x = 2$. D = 8, U = 6. Speed of stream = $\frac{8 - 6}{2} = 1$ km/h.

Question 8

8. A boat moves downstream at the rate of 1 km in 7.5 minutes and upstream at the rate of 5 km an hour. What is the speed of the boat in still water?

A) 6 km/hB) 5.5 km/hC) 6.5 km/hD) 7 km/h

Answer

✓ Correct Answer: Option C

Explanation: Solution: Downstream speed $D = \frac{1}{7.5/60} = \frac{60}{7.5} = 8$ km/h. Upstream speed U = 5 km/h. Speed in still water $B = \frac{D + U}{2} = \frac{8+5}{2} = 6.5$ km/h.

Question 9

9. Speed of a boat in standing water is 9 km/h and the speed of the stream is 1.5 km/h. A man rows to a place at a distance of 105 km and comes back to the starting point. The total time taken by him is:

A) 20 hoursB) 24 hoursC) 28 hoursD) 18 hours

Answer

✓ Correct Answer: Option B

Explanation: Solution: D = 9 + 1.5 = 10.5 km/h; U = 9 - 1.5 = 7.5 km/h. Total time = $\frac{105}{10.5} + \frac{105}{7.5}$ = 10 + 14 = 24 hours.

Question 10

10. The speed of a boat in still water is 10 km/h. If it can travel 26 km downstream and 14 km upstream in the same time, the speed of the stream is:

A) 2 km/hB) 4 km/hC) 2.5 km/hD) 3 km/h

Answer

✓ Correct Answer: Option D

Explanation: Solution: Let speed of stream be x. Time downstream = Time upstream. $\frac{26}{10 + x} = \frac{14}{10 - x} ⇒ 26(10 - x) = 14(10 + x)$. 260 - 26x = 140 + 14x ⇒ 40x = 120 ⇒ x = 3 km/h.

Accepted Answer

✓ Correct Answer: Option C

Explanation: Solution: Let u be upstream and d be downstream speed. $\frac{24}{u} + \frac{28}{d} = 6$ and $\frac{30}{u} + \frac{21}{d} = 6.5$. Solving these equations, we get u = 6 and d = 14. Speed of stream $v = \frac{d - u}{2} = \frac{14 - 6}{2} = 4$ km/h.

Competitive Exams : Quantitative Aptitude - Boats (Set 2)

1. The ratio of the speed of a boat in still water to the speed of the stream is 8 : 1. If the boat travels 36 km downstream in 2 hours, find the speed of the stream.

2. A boat covers 24 km upstream and 28 km downstream in 6 hours. It covers 30 km upstream and 21 km downstream in 6.5 hours. The speed of the stream is:

3. A man can row 6 km/h in still water. If the speed of the current is 2 km/h, it takes him 3 hours more to go upstream than downstream for the same distance. The distance is:

4. A boatman goes 2 km against the current of the stream in 1 hour and goes 1 km along the current in 10 minutes. How long will it take him to go 5 km in stationary water?

5. The speed of a boat in still water is 15 km/h and the speed of the current is 3 km/h. The distance travelled downstream in 12 minutes is:

6. A boat takes half the time to move a certain distance downstream than upstream. What is the ratio between the speed of the boat in still water and the speed of the current?

7. A man rows to a place 48 km distant and back in 14 hours. He finds that he can row 4 km with the stream in the same time as 3 km against the stream. The rate of the stream is:

8. A boat moves downstream at the rate of 1 km in 7.5 minutes and upstream at the rate of 5 km an hour. What is the speed of the boat in still water?

9. Speed of a boat in standing water is 9 km/h and the speed of the stream is 1.5 km/h. A man rows to a place at a distance of 105 km and comes back to the starting point. The total time taken by him is:

10. The speed of a boat in still water is 10 km/h. If it can travel 26 km downstream and 14 km upstream in the same time, the speed of the stream is: