Aptitude - Boats and Streams - Discussion
Discussion Forum : Boats and Streams - General Questions (Q.No. 13)
13.
Speed of a boat in standing water is 9 kmph and the speed of the stream is 1.5 kmph. 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:
Answer: Option
Explanation:
Speed upstream = 7.5 kmph.
Speed downstream = 10.5 kmph.
 Total time taken = |
 |
105 | + | 105 |  hours = 24 hours. |
| 7.5 | 10.5 |
Discussion:
24 comments Page 3 of 3.
VIJAY . C said:
6 years ago
Upstream speed = 9 - 1.5 = 7.5kmph.
Downstream speed = 9+1.5 = 10.5kmph.
D = S * T
D = 105kmph, S in upstream = 7.5kmph.
T has taken in upstream = 105/7.5.
Similarly,
T has taken in downstream = 105/10.5.
Total time taken = ( 105/7.5.)+ (105/10.5).
Multiply by 10,
T = (105*10/75) + (105*10/105).
T = 14 + 10.
T = 24hrs.
Downstream speed = 9+1.5 = 10.5kmph.
D = S * T
D = 105kmph, S in upstream = 7.5kmph.
T has taken in upstream = 105/7.5.
Similarly,
T has taken in downstream = 105/10.5.
Total time taken = ( 105/7.5.)+ (105/10.5).
Multiply by 10,
T = (105*10/75) + (105*10/105).
T = 14 + 10.
T = 24hrs.
Ranvijay said:
5 years ago
How it is taken 7.5 for upstream? please explain.
Rajat Kumar Kara said:
4 years ago
Guys, It's given the Speed of a boat in standing water and asking for the time taken by man to travel upstream and downstream. How you guys calculate upstream and downstream for the man?
Can't get it, Please explain.
Can't get it, Please explain.
Prasad Nangarale said:
3 years ago
Upstream speed = 9 - 1.5 = 7.5kmph.
Downstream speed = 9+1.5 =10.5kmph.
s = d/t
t = d/s...[in both case of upstream and downstream so addition of both].
t = 105/7.5 + 105/10.5.
Multiply by 10, to remove the denominator point;
t = (105*10/75) + (105*10/105).
t= 14 + 10.
t= 24hrs.
Downstream speed = 9+1.5 =10.5kmph.
s = d/t
t = d/s...[in both case of upstream and downstream so addition of both].
t = 105/7.5 + 105/10.5.
Multiply by 10, to remove the denominator point;
t = (105*10/75) + (105*10/105).
t= 14 + 10.
t= 24hrs.
(6)
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