Question

A train takes 2½ hours less for a journey of 300 km, if its speed is increased by 20 km/h from its usual
speed. How much time will it take to cover a distance of 192 km at its usual speed?

a) 6 hours
b) 4.8 hours
c) 3 hours
d) 2.4 hours​

Answer 1

Answer:

4.8hours

Step-by-step explanation:

Let X be the usual speed

300/x - 300/x+20=5/2

Taking lcm to be x(x+20) then:

X²+20x-2400(in the simplified form)

The roots of the quadratic equation are:

X=40 or x=-60(disqualified)

So 40 is the usual speed.

Time=distance/speed

=192km/40km/hr

=4.8hours

=4.8 hours