Quantitative Aptitude

Boats and Streams

369 Questions
All Recover still-water and stream speeds 136 Calculate one-way and round-trip time 61 Ratio of boat to stream speed 54 Use time differences and equal-distance ratios 39 Perpendicular river crossing 36 Round-trip average speed 14 Angles of drift 12 Handle drifting objects 8 Solve meeting and separation problems 6 Fixed-time distance ratios 3

Boats and Streams Questions

Multiple choice

Compare Quantity A and Quantity B, using additional information centered above the two quantities if such information is given, and select one of the following answer choices: Quantity A = A boat rows upstream 16 km and downstream 27 km talking 5 hours each time. What is the velocity of current? Quantity B = A boat moves downstream at the rate of one km in 7(1/2) minutes and upstream at the rate of 5 km an hour. What is the velocity of current?

  1. Quantity A is greater than Quantity B

  2. Quantity B is greater than Quantity A

  3. Quantity B is greater or equal to Quantity A

  4. Quantity A is greater or equal to Quantity B

  5. Both are equal or the relationship cannot be determined from the information given
Reveal answer Fill a bubble to check yourself
B Correct answer
Explanation

Quantity A: Upstream speed = 16/5 = 3.2 km/h. Downstream speed = 27/5 = 5.4 km/h. Current = (5.4 - 3.2)/2 = 1.1 km/h. Quantity B: Downstream speed = 1 km / (7.5/60) h = 8 km/h. Upstream speed = 5 km/h. Current = (8 - 5)/2 = 1.5 km/h. Since 1.5 > 1.1, B is greater.

Multiple choice

Directions: You are given two quantities, Quantity I and Quantity II. Compare the two quantities and choose the correct option accordingly. Speed of a boat in still water and speed of the current are in the ratio 7 : 3. The difference between distances covered by the boat going 2 hr upstream and 2 hr downstream is 36 km. Quantity I: Speed of the boat in still water Quantity II: Speed of the rubber bullet that covers 10 m in 2 seconds

  1. Quantity I > Quantity II

  2. Quantity I < Quantity II

  3. Quantity I = Quantity II

  4. No relation
Reveal answer Fill a bubble to check yourself
A Correct answer
Explanation

Let boat speed = 7x, current = 3x. Upstream = 4x, Downstream = 10x. Distance diff = 2(10x) - 2(4x) = 36 => 12x = 36 => x = 3. Boat speed = 21 km/h. Quantity II: 10m / 2s = 5 m/s = 18 km/h. 21 > 18.

Multiple choice

Directions: You are given two quantities, Quantity I and Quantity II. Compare the two quantities and choose the correct option accordingly. In a river, the speed of a boat and the speed of the stream are in the ratio 5 : 2, and the speed of another boat and the speed of the stream are in the ratio 4 : 3. Quantity I: Speed of the first boat Quantity II: Speed of the second boat

  1. Quantity I > Quantity II

  2. Quantity I < Quantity II

  3. Quantity I = Quantity II

  4. No relation
Reveal answer Fill a bubble to check yourself
A Correct answer
Multiple choice

In a river, the ratio of the speed of the stream and the speed of a boat in still water is 5 : 7. Again, the ratio of the speed of the stream to the speed of another boat in still water is 6 : 8. What is the ratio of the speed of the first boat to that of the second boat in still water? একটি নদীতে স্রোতের বেগ এবং স্থির জলে নৌকার বেগ এর অনুপাত হল 5:7। পুনরায় স্রোতের বেগ এবং অপর একটি নৌকার স্থির জলে বেগের অনুপাত 6:8। তাহলে স্থির জলে প্রথম নৌকা এবং দ্বিতীয় নৌকার বেগের অনুপাত কত

  1. 19 : 17

  2. 27 : 28

  3. 21 : 20

  4. 27 : 29
Reveal answer Fill a bubble to check yourself
C Correct answer
Explanation

Stream speed S. Boat 1 speed B1 = 7/5 * S. Boat 2 speed B2 = 8/6 * S = 4/3 * S. Ratio B1/B2 = (7/5) / (4/3) = 21/20.

Multiple choice

A boat can cover 32 km upstream in 4 hours. Ratio of the speed of boat in still water to the speed of current is 5 : 1. In how much time can the boat cover 60 km downstream?

  1. 6 hours

  2. 5 hours

  3. 5.5 hours

  4. 7 hours

  5. 4 hours
Reveal answer Fill a bubble to check yourself
B Correct answer
Explanation

Upstream speed = 32/4 = 8 km/h. Let boat speed be 5x and current be 1x. Upstream speed = 5x - 1x = 4x. So 4x = 8, x = 2. Boat speed = 10, current = 2. Downstream speed = 10 + 2 = 12 km/h. Time for 60 km = 60/12 = 5 hours.

Multiple choice

P, Q and R are three towns on a river which flows uniformly. Q is equidistant from P and R. I row from P to Q and back in 10 hours and I can row from P to R in 4 hours. Compare the speed of my boat in still water with that of the river.

  1. 4 : 3

  2. 5 : 3

  3. 6 : 5

  4. 7 : 3
Reveal answer Fill a bubble to check yourself
B Correct answer
Explanation

Let b be boat speed, r be river speed. P to Q is distance d. P to R is 2d. Time P to Q and back: d/(b-r) + d/(b+r) = 10. Time P to R: 2d/(b+r) = 4 => d/(b+r) = 2. Substitute: d/(b-r) + 2 = 10 => d/(b-r) = 8. Ratio (b+r)/(b-r) = 8/2 = 4. b+r = 4b-4r => 3b = 5r. b/r = 5/3.

Multiple choice

In a river, the ratio of the speed of stream and speed of a boat A in still water is 2 : 5. Again, in the same river ratio of the speed of stream and speed of an another boat B in still water is 3 : 4. What is the ratio of the speeds of the boat A to the boat B in still water ?(if speed of stream is same in both conditions.)

  1. 10 : 7

  2. 15 : 8

  3. 4 : 3

  4. 5 : 4
Reveal answer Fill a bubble to check yourself
B Correct answer
Explanation

Let S be the speed of the stream. Boat A: S/A = 2/5 -> A = 2.5S. Boat B: S/B = 3/4 -> B = (4/3)S. The ratio A:B = 2.5S : (4/3)S = 2.5 : 1.333 = 7.5 : 4 = 15 : 8.

Multiple choice

A boat can go 10 km downstream and 8 km upstream in 49 minutes. Also it can go 12 km downstream and 4 km upstream in 42 minutes. What is the speed of stream in km/h?

  1. 1.5

  2. 1

  3. 2

  4. 2.5
Reveal answer Fill a bubble to check yourself
C Correct answer
Explanation

Let the downstream speed be d and the upstream speed be u. From the given conditions, we get the equations 10/d + 8/u = 49/60 and 12/d + 4/u = 42/60. Solving these equations gives d = 24 km/h and u = 20 km/h. The speed of the stream is half the difference of these speeds, which is (24 - 20)/2 = 2 km/h.