1000 m/sec ના વેગથી એક ગોળી 100 m દૂર આવેલ

Bullet will take $\frac{{100}}{{1000}} = 0.1$sec to reach target.

During this period vertical distance (downward)travelled by the bullet

$ = \frac{1}{2}g{t^2}$$ = \frac{1}{2} \times 10 \times {(0.1)^2}m = 5\;cm$

So the gun should be aimed 5 cm above the target.