A man walking at 3 km/hour crosses a square field diagonally in 2 minutes. The area of the field (in square metre) is

Speed of person = 3 kmph

$=\left(\frac{3000}{60}\right) \mathrm{m} . / \mathrm{min} .$

$=50 \mathrm{~m} . / \mathrm{min} .$

∴ Length of the diagonal of square field

= 50 × 2 = 100 metre

$\therefore$ Required area $=\frac{1}{2} \times(100)^{2}$ $=5000$ sq. metre