Question

speed of a boat in still water in 15km/h. It goes 30km upstream and return back at the same point in 4h 30min. Find the speed of the stream ​

Answer 1

Answer:

5 km/h

Step-by-step explanation:

Speed of stream= x km/h

Speed of boat in still water =15km/h

Distance upstream= 30 km

Distance downstream= 30 km

Time taken = 4 1/2 h

Speed of boat upstream= (15-x)km/h

Speed of boat dowmstream= (15-x)km/h

Acc. to quest.,

30/(15-x) + 30/(15+x) = 4 1/2

900/225-x ^2 =9/2

1800=9(225-x^2)

1800=2025-9x^2

9x^2=2025-1800

9x^2=225

x^2=225÷9

x^2=25

x=sq.root 25

x= 5

Therefore speed of stream is 5 km/h