1. A boat can travel with a speed of 13 km/hr in still water. If the speed of the stream is 4 km/hr, find the time taken by the boat to go 68 km downstream.
A. 2 hours B. 3 hours
C. 4 hours D. 5 hours
Answer & Explanation
Answer: Option C
Explanation:
Speed downstream = (13 + 4) km/hr = 17 km/hr.
Time taken to travel 68 km downstream =
68
17 hrs = 4 hrs.
2. A man's speed with the current is 15 km/hr and the speed of the current is 2.5 km/hr. The man's speed against the current is:
A. 8.5 km/hr B. 9 km/hr
C. 10 km/hr D. 12.5 km/hr
Answer & Explanation
Answer: Option C
Explanation:
Man's rate in still water = (15 - 2.5) km/hr = 12.5 km/hr.
Man's rate against the current = (12.5 - 2.5) km/hr = 10 km/hr.
3. In one hour, a boat goes 11 km/hr along the stream and 5 km/hr against the stream. The
speed of the boat in still water (in km/hr) is:A. 3 km/hr B. 5 km/hr
C. 8 km/hr D. 9 km/hr
Answer & Explanation
Answer: Option C
Explanation:Speed in still water = 1 /2 (11 + 5) kmph = 8 kmph.
4.A boat running downstream covers a distance of 16 km in 2 hours while for covering the same
distance upstream, it takes 4 hours. What is the speed of the boat in still water?
A. 4 km/hr B. 6 km/hr
C. 8 km/hr D. Data inadequate
Answer & Explanation
Answer: Option B
Explanation:
Rate downstream =(16/2)kmph= 8 kmph.
Rate upstream = (16/4)kmph= 4 kmph.
:Speed in still water =1/2(8+4)kmph = 6 kmph.
5.The speed of a boat in still water in 15 km/hr and the rate of current is 3 km/hr. The distance
travelled downstream in 12 minutes is:
A. 1.2 km B. 1.8 km
C. 2.4 km D. 3.6 km
Answer & Explanation
Answer: Option D
Explanation:
Speed downstream = (15 + 3) kmph = 18 kmph.
Distance travelled =(18x12/60)km = 3.6 km.
6.A boat covers a certain distance downstream in 1 hour, while it comes back in 1 hours. If the speed of the stream be 3 kmph, what is the speed of the boat in still water?
A. 12 kmph B. 13 kmph
C. 14 kmph D. 15 kmph
E. None of these
Answer & Explanation
Answer: Option D
Explanation:
Let the speed of the boat in still water be x kmph. Then,
Speed downstream = (x + 3) kmph,
Speed upstream = (x - 3) kmph.
(x + 3) x 1 = (x - 3) x 3/2
--> 2x + 6 = 3x - 9
--> x = 15 kmph.
A. 2 hours B. 3 hours
C. 4 hours D. 5 hours
Answer & Explanation
Answer: Option C
Explanation:
Speed downstream = (13 + 4) km/hr = 17 km/hr.
Time taken to travel 68 km downstream =
68
17 hrs = 4 hrs.
2. A man's speed with the current is 15 km/hr and the speed of the current is 2.5 km/hr. The man's speed against the current is:
A. 8.5 km/hr B. 9 km/hr
C. 10 km/hr D. 12.5 km/hr
Answer & Explanation
Answer: Option C
Explanation:
Man's rate in still water = (15 - 2.5) km/hr = 12.5 km/hr.
Man's rate against the current = (12.5 - 2.5) km/hr = 10 km/hr.
3. In one hour, a boat goes 11 km/hr along the stream and 5 km/hr against the stream. The
speed of the boat in still water (in km/hr) is:A. 3 km/hr B. 5 km/hr
C. 8 km/hr D. 9 km/hr
Answer & Explanation
Answer: Option C
Explanation:Speed in still water = 1 /2 (11 + 5) kmph = 8 kmph.
4.A boat running downstream covers a distance of 16 km in 2 hours while for covering the same
distance upstream, it takes 4 hours. What is the speed of the boat in still water?
A. 4 km/hr B. 6 km/hr
C. 8 km/hr D. Data inadequate
Answer & Explanation
Answer: Option B
Explanation:
Rate downstream =(16/2)kmph= 8 kmph.
Rate upstream = (16/4)kmph= 4 kmph.
:Speed in still water =1/2(8+4)kmph = 6 kmph.
5.The speed of a boat in still water in 15 km/hr and the rate of current is 3 km/hr. The distance
travelled downstream in 12 minutes is:
A. 1.2 km B. 1.8 km
C. 2.4 km D. 3.6 km
Answer & Explanation
Answer: Option D
Explanation:
Speed downstream = (15 + 3) kmph = 18 kmph.
Distance travelled =(18x12/60)km = 3.6 km.
6.A boat covers a certain distance downstream in 1 hour, while it comes back in 1 hours. If the speed of the stream be 3 kmph, what is the speed of the boat in still water?
A. 12 kmph B. 13 kmph
C. 14 kmph D. 15 kmph
E. None of these
Answer & Explanation
Answer: Option D
Explanation:
Let the speed of the boat in still water be x kmph. Then,
Speed downstream = (x + 3) kmph,
Speed upstream = (x - 3) kmph.
(x + 3) x 1 = (x - 3) x 3/2
--> 2x + 6 = 3x - 9
--> x = 15 kmph.
Posts
Comment Policy : We invite you to comment on our posts, as long as they are respectful, to the point and approving. We do not perform pre-moderation of comments. However, in order to keep this site clean and useful, we reserve the right to remove any comment that is not in accordance with our Comment Policy.