Mathematics Mcqs

A boat goes 24 km downstream in 10 hours, it takes 2 hours more to cover the same distance against the stream. What is the speed of the boat in still water?

by
A boat goes 24 km downstream in 10 hours, it takes 2 hours more to cover the same distance against the stream. What is the speed of the boat in still water?

A. 2km/hr
B. 2.8 km/hr
C. 4 km/hr
D. 4.2 km/hr
E. None of these
Explanation:
Speed downstream = 24/10 km/hr = 2.4 km/hr
Speed upstream = 24/12 km/hr = 2 km/hr
Speed of the boat in still water = ½ (2.4 +2)km/hr = 2.2 km/hr

A boat running downstream covers 24 km’s in 4 hours while for covering the same distance upstream it takes 6 hours whats the speed of the boat in still water?

by
A boat running downstream covers 24 km’s in 4 hours while for covering the same distance upstream it takes 6 hours whats the speed of the boat in still water?

A. 3.5km/hr
B. 5.5 km/hr
C. 6 km/hr
D. Data Inadequate
E. None of these
Explanation:
Speed downstream = 24/4 km/hr = 6 km/hr
Speed upstream = 24/6 km/hr = 4 km/hr
Speed of the boat in still water = ½ (6 +4)km/hr = 5 km/hr

A person can row at 9 kmph and still water. He takes 4 1/2 hours to row from A to B and back. What is the distance between A and B if the speed of the stream is 1 kmph?

by
A person can row at 9 kmph and still water. He takes 4 1/2 hours to row from A to B and back. What is the distance between A and B if the speed of the stream is 1 kmph?

A. 32 km
B. 25 km
C. 28 km
D. 24 km
E. None of these
Explanation:
Let the distance between A and B be x km.
Total time = x/(9 + 1) + x/(9 – 1) = 4.5
=> x/10 + x/8 = 9/2 => (4x + 5x)/40 = 9/2 => x = 20 km.

The speed at which a man can row a boat in still water is 15 kmph. If he rows downstream, where the speed of current is 3 kmph, what time will he take to cover 60 metres?

by
The speed at which a man can row a boat in still water is 15 kmph. If he rows downstream, where the speed of current is 3 kmph, what time will he take to cover 60 metres?

A. 10 seconds
B. 15 seconds
C. 20 seconds
D. 12 seconds
E. None of these
Explanation:
Speed of the boat downstream = 15 + 3 = 18 kmph
= 18 * 5/18 = 5 m/s
Hence time taken to cover 60 m = 60/5 = 12 seconds.

A man can row downstream at 18 kmph and upstream at 10 kmph. Find the speed of the man in still water and the speed of stream respectively?

by
A man can row downstream at 18 kmph and upstream at 10 kmph. Find the speed of the man in still water and the speed of stream respectively?

A. 13, 3
B. 12, 6
C. 15, 3
D. 14, 4
Explanation:
Let the speed of the man in still water and speed of stream be x kmph and y kmph respectively.
Given x + y = 18 — (1)
and x – y = 10 — (2)
From (1) & (2) 2x = 28 => x = 14, y = 4.

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?

by
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
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.

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?

by
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
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.

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?

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

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?

by
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
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