Question no : 13 A train will take 20 minutes more to travel 50 km distance if the speed is decreased by 5 km/hr. Find the usual speed.
Answers
Answered by
1
Answer :
30 km /hr
Step-by-step explanation:
let usual speed is x and time is y
if speed decreased by 5 then new speed is x-5
new time - actual time = change in time
50/(x-5) - 50/x = 20/60
3(50x -50(x-5)) = x(x-5)
150x -150x + 750 = x^2 -5x
x^2- 5x -750= 0
(x-30)(x+25) =0
x = 30 or -25 km/hr
but speed cant be -ve
so answer is 30
Similar questions