Question

The speed of a boat in still water is 15 km/h.It can go 30 km/h and return downstream and return to its original point in 4 hours 30 minutes.Find speed of stream.

Answer 1

Speed of boat tn still water = 15 km/h
upstream + downstream = 3o km
t1 (upstram) = 30 /15-x
t2 (downstream ) =30 /15 +x
total time (4 hours 30 miutes = 9/2 hours)

so equation is 30/15-x + 30/15+x=9/2
solve this equation
after solving x will be 5.
So answer is 5

Answer 2

Hey there!

Let speed of stream = x km/h

∴ Downstream speed = (15+x) km/h

∴ Upstream speed = (15-x) km/h

∴ 30/(15+x) + 30/(15-x) = 4 1/2

→ 900/225-x² = 9/2

→ 9x² = 225

→ x² = 25

→ x = 5

∴ Speed of stream = 5 km/h

Hope it Helps You!