Discussion

Find the area of the square field if a train 800 metres long passes the field with a speed of 120 kmph in one minute.

Answer: A

In one minute the train travels

\[ 120 \text{ kmph} = \frac{120000}{60} = 2000 \text{ m/min} \]

To pass the field, the train must cover the field's length plus its own length:

\[ \text{side} = 2000 - 800 = 1200 \text{ m} = 1.2 \text{ km} \]

\[ \text{area} = (1.2)^{2} = 1.44 \text{ sq. km} \]

Forgetting to subtract the train's own length would give a 2 km side and an area of 4 sq. km - exactly the second option.

No comment is present. Be the first to comment.

Loading…