Question

A journey of 1600 km by an express
train takes 24 hours less than by an
ordinary train. I the ordinary train is
15km/hour slower than the express
train, then find the speed of the express
train
(A) 40 km/hr.
(8) 125 km/hr.
(0) 65 km/hr.
Di None of these​

Answer 1

Answer:

40

Step-by-step explanation:

as per the option if we put one by one we will get the answer

Answer 2

Answer:

64km/hr that's why answer is D) None of these

Step-by-step explanation:

Distance=1600

for express train speed -15 = ordinary train speed

time for ordinary train be X and express train be X-24

s = d/t....(for express train)

s = 1600/X -24.......(1)

s = d/t.....( for ordinary train)

s - 15= 1600/ X........(2)

put,s=1600/X-24

1600/X-24 - 15 = 1600/X

1600/X-24 - 1600/X = 15

1600(1/X -24-1/X ) =15

x-x-24/x^2-24x =15/1600

24/x^2 - 24x = 15/1600

38400 = 15x^2 - 360x

15x^2 - 360x -38400=0

x^2 - 24x - 2560= 0 ........( divide by 15)

x^2 - 64x + 40x - 2560=0

X(X -64) + 40( X - 64)= 0

(X + 40)(X - 64) = 0

X = -40. or X = 64

here, speed is never in negative

therefore speed= 64

ANSWER IS 64km/hr

hope this help you