63. A train overtakes two persons who are walking in the same direction in which the train is going, at the rate of 2 kmph and 4 kmph and passes them completely in 9 and 10 seconds respectively. The length of the train is:

✅ The correct answer is option B.
2 kmph =

2 x
5

m/sec =
5
m/sec.

18
9

4 kmph =

4 x
5

m/sec =
10
m/sec.

18
9

Let the length of the train be x metres and its speed by y m/sec.

Then,

x

= 9 and

x

= 10.

y –
5

9

y –
10

9

9y – 5 = x and 10(9y – 10) = 9x
9y – x = 5 and 90y – 9x = 100.
On solving, we get: x = 50.
Length of the train is 50 m.