Question

A train covers a distance of 90 km at a uniform speed. Had the speed been 15 km/hour
more it would have taken 30 minutes less for the journey. Find the original speed of the
train.
[CBSE 2006C)​

Answer 1

Answer:

Had the speed been 15 km/hour more, it would have taken 30 minutes less for a journey. Find the original speed of the train. Answer: → Original speed of the train = 45 km/hr .

Answer 2

Answer:

distance -90km

let original speed be xkm/hr

time - distance/time

t1- 90/X

distance -90km

speed increases by 15km/hr=(X+15)km/HR

T2 =90/X+15

given

t1- t2=30

90/x - 90/(X+15)=1/2

135×2=x²+15x

2700=x²+15x

x²+15x-2700=0

X(X+60)-45(X+60)

(x-45)(X+60)

X=45 X=-60

speed should be positive so X=40

speed = 45km/hr