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A train passes a telegraph post in 8 seconds and a 264 m long bridge in 20 seconds. What is the length of the train

Answer: B

A telegraph post has no length, so the first crossing covers only the train.

\[ L = 8v \]

The bridge crossing covers the train plus 264 m:

\[ L + 264 = 20v \]

Substituting the first into the second:

\[ 8v + 264 = 20v \quad\Longrightarrow\quad 12v = 264 \quad\Longrightarrow\quad v = 22 \text{ m/s} \]

\[ L = 8 \times 22 = 176 \text{ m} \]

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