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Question : A train passes by a lamp post on a platform in 7 seconds and passes by the platform completely in 28 seconds. If the length of the platform is 390 m, the length of the train (in metres) is:

Option 1: 120

Option 2: 130

Option 3: 140

Option 4: 150


Team Careers360 1st Jan, 2024
Answer (1)
Team Careers360 25th Jan, 2024

Correct Answer: 130


Solution : We have,
Length of the platform = 390 m
The time taken to cross a lamp post is 7 seconds.
The time taken to cross the platform is 28 seconds.
Let the length of the train be $x$ m.
Speed of the train = $\frac{\text{Distance}}{\text{Time}}$ = $\frac{x}{7}$ m/s
Length of the train + Length of the platform = Speed of train × Time
$⇒ x + 390 = \frac{x}{7} \times 28$
$⇒ x+390=4x$
$⇒ 3x=390$
$\therefore x=130$ m
Hence, the correct answer is 130.

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