ABoat takes 128 min less to travel to 48 Km downstream than to travel ...
Answer – 3. 12 Km/hr Explanation : 32/15 = 48(1/s-3 – 1/s+3) s= 12
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ABoat takes 128 min less to travel to 48 Km downstream than to travel ...
Given data:
Distance = 48 Km
Speed of stream = 3 Km/hr
Let the speed of the boat in still water be x km/hr
When the boat travels downstream:
Speed of the boat = (x + 3) km/hr
Time taken = distance/speed = 48/(x + 3) hr
When the boat travels upstream:
Speed of the boat = (x - 3) km/hr
Time taken = distance/speed = 48/(x - 3) hr
According to the question,
Time taken downstream - Time taken upstream = 128 min
i.e., 48/(x + 3) - 48/(x - 3) = 128/60
Simplifying this equation, we get:
12x = 169
x = 169/12 = 14.083 km/hr
Therefore, the speed of the boat in still water is 14.083 km/hr, which is closest to option C (12 km/hr).
ABoat takes 128 min less to travel to 48 Km downstream than to travel ...
Speed of stream = 3km/hr
Distance = 48km
consider T1=time during downstream
T2=time during upstream
Condition given: T2-T1=128minutes = 128/60 hours
To find : SPEED OF BOAT IN STILL WATER (let's assume u)
Solution :- T2= 48/(u-3)
T1=48/(u+3)
using: T2-T1= 128/60
48/(u-3) - 48/(u+3)= 128/60
After taking LCM we get
288/(u²-9) =128/60
u²-9=(288×60)/128
u²-9= 15×9
u²= 135+9
u²= 144
u=12km/hr
so option C is the correct answer