Question

To travel 720 km, a express train takes 6 hours more than duronto. if however, the speed of the express train is doubled, it takes 2 hours less than duronto. the speed of duronto (in km/hr) is?

Answer 1

Answer:

The speed of duronto is 72 km/h.

Step-by-step explanation:

Let x be the speed of express train and y be the speed of duronto,

Since, Time = Distance / Speed,

Given,

To travel 720 km, a express train takes 6 hours more than duronto.

$\implies \frac{720}{x}=\frac{720}{y}+6$

Let, 720/x = A and 720/y = B,

$\implies A = B + 6-------(1)$ ,

Now, if the speed of the express train is doubled, it takes 2 hours less than duronto.

$\frac{720}{2x}=\frac{720}{y}-2$

$\frac{A}{2}=B-2$

$\implies A = 2B - 4-------(2)$

From equation (1) and (2),

B + 6 = 2B - 4

⇒ B = 10

From equation (1),

A = 16

⇒ 720/x = 16 ⇒ x = 45 and 720/y = 10 ⇒ y = 72

Hence, the speed of duronto is 72 km/h.