A train $240m$ long passes a pole in $24sec$. How long will it take to pass a platform which is $650m$ long?

The correct option is B

$89$ $sec$

Step 1. Find the Speed of train.

Speed of train $=\frac{lengthoftrain}{timetocrosspole}$

$$\begin{gathered} =\frac{240}{24} \\ =10m/sec \end{gathered}$$

Step 2: Find total distance covered by train.

When train crosses a platform of length $650m$ long

Then total distance cover by train $=$length of train + length of platform

$$\begin{gathered} =240+650 \\ =890m \end{gathered}$$

Step 3: Find the time taken to cross the platform.

Time taken to cross the platform $=\frac{totaldis\tan cecoverbytrain}{speddoftrian}$

$$\begin{gathered} =\frac{890}{10} \\ =89sec \end{gathered}$$

Hence, total time taken by train to cross the platform is $89sec$.