Question

A train travelling at a speed of 75 mph enters a tunnel 3 $\frac{1}{2}$miles long. The train is $\frac{1}{4}$mile long. How long does it take for the train to pass through the tunnel from the moment the front enters to the moment the rear emerges?

• A. $2min$
• B. $3min$
• C. $4min$
• D. $5min$

Answer 1

The correct option is B $3min$

Speed of the train $=75mph$

Length of the tunnel$=3\frac{1}{2}miles$

$=\frac{7}{2}miles$

Length of the train$=\frac{1}{4}miles$

Time taken to pass through the tunnel $=\frac{\frac{7}{2}+\frac{1}{4}}{75}$

$=\frac{\frac{15}{4}}{75}$

$=\frac{15}{4\times 75}$

$=\frac{1}{20}hrs$

$=\frac{1}{20}\times 60min$

$=3minutes$