Boats & Streams Mcqs - Set 2

1)   A man can row 30 km downstream and 20 km upstream in 4 hours. He can row 45 km downstream and 40 km upstream in 7 hours. Find the speed of man in still water?

a. 15 kmph
b. 10 kmph
c. 12 kmph
d. 12.5 kmph
e. None of these
Answer  Explanation 

ANSWER: 12.5 kmph

Explanation:
Let the speed of the man in still water be a kmph and let the speed of the stream be b kmph.

Now 30/(a + b) + 20/(a – b) = 4 and 45/(a + b) + 40/(a – b) = 7
Solving the equation, the speed of man in still water is 12.5 kmph.

2)   The time taken by a man to row his boat upstream is twice the time taken by him to row the same distance downstream. If the speed of the boat in still water is 42 kmph, find the speed of the stream?

a. 12 kmph
b. 13 kmph
c. 14 kmph
d. 15 kmph
Answer  Explanation 

ANSWER: 14 kmph

Explanation:
The ratio of the times taken is 2:1.
The ratio of the speed of the boat in still water to the speed of the stream = (2+1)/(2-1) = 3/1 = 3:1
Speed of the stream = 42/3 = 14 kmph.

3)   A man can row a boat at 20 kmph in still water. If the speed of the stream is 6 kmph, what is the time taken to row a distance of 60 km downstream?

a. 20/6 hours
b. 27/2 hours
c. 30 hours
d. 30/13 hours
Answer  Explanation 

ANSWER: 30/13 hours

Explanation:
Speed downstream = 20 + 6 = 26 kmph.
Time required to cover 60 km downstream = d/s = 60/26 = 30/13 hours.

4)   A man rows his boat 85 km downstream and 45 km upstream, taking 2 1/2 hours each time. Find the speed of the stream?

a. 5 kmph
b. 6 kmph
c. 7 kmph
d. 8 kmph
Answer  Explanation 

ANSWER: 8 kmph

Explanation:
Speed downstream = d/t = 85/(2 1/2) = 34 kmph
Speed upstream = d/t = 45/(2 1/2) = 18 kmph
The speed of the stream = (34 – 18)/2 = 8 kmph

5)   The speed of a boat in upstream is 60 kmph and the speed of the boat downstream is 80 kmph. Find the speed of the boat in still water and the speed of the stream?

a. 70, 10 kmph
b. 35, 27 kmph
c. 50, 60 kmph
d. 45, 55 kmph
Answer  Explanation 

ANSWER: 70, 10 kmph

Explanation:
Speed of the boat in still water = (60+80)/2 = 70 kmph. Speed of the stream = (80-60)/2 = 10 kmph.

6)   The speed of a boat in still water is 60kmph and the speed of the current is 20kmph. Find the speed downstream and upstream?

a. 35, 25 kmph
b. 80, 40 kmph
c. 40, 60 kmph
d. 50, 55 kmph
Answer  Explanation 

ANSWER: 80, 40 kmph

Explanation:
Speed downstream = 60 + 20 = 80 kmph
Speed upstream = 60 – 20 = 40 kmph

7)   The current of a stream at 1 kmph. A motor boat goes 35 km upstream and back to the starting point in 12 hours. The speed of the motor boat in still water is_________?

a. 6 kmph
b. 7 kmph
c. 8.5 kmph
d. 8 kmph
Answer  Explanation 

ANSWER: 6 kmph

Explanation:
S = 1
M = x
DS = x + 1
US = x – 1
35/(x + 1) + 35/(x – 1) = 12
x = 6

8)   A man whose speed is 4.5 kmph in still water rows to a certain upstream point and back to the starting point in a river which flows at 1.5 kmph, find his average speed for the total journey?

a. 8 kmph
b. 4 kmph
c. 2 kmph
d. 10 kmph
Answer  Explanation 

ANSWER: 4 kmph

Explanation:
M = 45
S = 1.5
DS = 6
US = 3
AS = (2 * 6 * 3) /9 = 4

9)   The current of a stream runs at the rate of 4 kmph. A boat goes 6 km and back to the starting point in 2 hours, then find the speed of the boat in still water?

a. 10 kmph
b. 21 kmph
c. 8 kmph
d. 12 kmph
Answer  Explanation 

ANSWER: 8 kmph

Explanation:
S = 4
M = x
DS = x + 4
US = x – 4
6/(x + 4) + 6/(x – 4) = 2
x = 8

10)   A man can row 6 kmph in still water. When the river is running at 1.2 kmph, it takes him 1 hour to row to a place and black. What is the total distance traveled by the man?

a. 6.24 km
b. 6 km
c. 5.76 km
d. 5.66 km
Answer  Explanation 

ANSWER: 5.76 km

Explanation:
M = 6
S = 1.2
DS = 7.2
US = 4.8
x/7.2 + x/4.8 = 1
x = 2.88
D = 2.88 * 2 = 5.76

Related Content

▲