72.A
boatman goes 2 km against the current of the stream in 1 hour and goes 1 km
along the current in 10 minutes. How long will it take to go 5 km in stationary
water?
A. 40 minutes B. 1 hour
C. 1 hr 15 min D. 1 hr 30
min
Answer: Option C
Explanation:
|
Rate
downstream =
|
|
1
|
x
60
|
km/hr
= 6 km/hr.
|
|
10
|
Rate
upstream = 2 km/hr.
|
Speed
in still water =
|
1
|
(6
+ 2) km/hr = 4 km/hr.
|
|
2
|
|
Required
time =
|
|
5
|
hrs
= 1
|
1
|
hrs
= 1 hr 15 min.
|
|
4
|
4
|
