A train 132 m long passes a telegraph pole in 6 seconds. Find the speed of the train.

### Concept & Formula To find the speed of a train crossing a pole, divide its length by the time taken. The result will be in meters per second (m/s), which must be converted to kilometers per hour (km/hr) by multiplying by $\frac{18}{5}$. $$ \text{Speed (m/s)} = \frac{\text{Distance}}{\text{Time}} $$ $$ \text{Speed (km/hr)} = \text{Speed (m/s)} \times \frac{18}{5} $$ ### Step-by-Step Solution * **Given:** Distance (Length) = $132$ m, Time = $6$ seconds. * **Calculate Speed in m/s:** $\text{Speed} = \frac{132}{6} = 22$ m/s. * **Convert to km/hr:** $\text{Speed} = 22 \times \frac{18}{5}$. * Multiply the numerators: $22 \times 18 = 396$. * Divide by $5$: $\frac{396}{5} = 79.2$ km/hr. ### Exam Strategy & Shortcut To divide any number by $5$ quickly, multiply it by $2$ and shift the decimal point one place to the left. For $\frac{396}{5}$: $396 \times 2 = 792$, shifting the decimal gives $79.2$. ### Common Pitfall Forgetting to convert the final answer from m/s to km/hr, or using the wrong conversion multiplier ($\frac{5}{18}$ instead of $\frac{18}{5}$). ### Final Answer Therefore, the correct answer is **79.2 km/hr**.