Question

a speed of a Boat in still water is 11 km per hour it can go 12 km upstream and return downstream to the original point in 2 hours 45 minutes find the speed of the stream???

Answer 1

Let the speed of stream be x

Speed of boat in still water = 11
Speed of boat upstream = 11-x
Speed of boat downstream = 11+x

Distance = 12
Distance/speed = time

12/(11-x) + 12/(11+x) = 2 hours 45min
12*(22/(121-x^2) = 11/4
x^2 = 25
x = 5

Speed of stream = 5km/hr

Answer 2

Answer:

Step-by-step explanation:

Solution :-

Let the speed of the stream be x km/hr.

Speed of boat upstream = 11 - x 

Speed of boat downstream = 11 + x

 According to the Question,

⇒ 12/11 - x + 12/11 + x= 2 3/4 

⇒ 12(1/11 - x + 1/11 + x) = 11/4 

⇒ 22/121 - x² = 11/4 × 12

⇒ 22/121 - x² = 11/48

⇒ 1331 - 11x² = 1056 

⇒ 11x² = 275 

⇒ x² = 25

⇒ x = 5 

Hence, the speed of stream is 5 km/hr.