Question

A train travels for 360 km. If its speed had been 10km/hr more it would take 3 hr less find the accurate speed.

Answer 1

Answer:

Let the speed of the train be x km/h

distance = 360 km

let the time taken = y hrs.

A.T.Q.,

x = 360/y _______eq. 1

A.T. second statement.,

x+10= 360/y-3__________eq. 2

putting value of x from eq.1 in 2

360/y +10=360/y-3

= 360/y - 360/y-3=-10

= (y-3)360-360y=-10(y)(y-3)

=360y-3*360-360y=-10(y^2-3y)

= -1080=-10(y^2-3y)

=108=y^2-3y

=y^2-3y-108= 0

using quadratic formula....

y={3+√(6+4×2×108)}/2×1

y=(3+30)/2

y=33/2

y=16.5 hours or 16 h 30 min.

from 1st eq.

x=360/y

x=360/16.5

x=21.81 km/h