Question

a bullet is fired with velocity 55m/sec at a target.if if the sound of collision heard after 7second.find the distance between target and gun.(speed of sound in air=330m/sec

Answer 1

7 seconds?

Answer 2

Call the time, which I think is a typo, T
distance is d

t1 = time out
t2 = time back

t1 + t2 = T
t1 = d/55
t2 = d/330
so
d/55 + d/330 = T
d = T /(1/55 + 1/330)

Answer 3

If the distance is x meters, then since time = distance/speed,

x/55 + x/330 = 7
x = 330m

Now, the problem is that the bullet will drop 176m in the 6 seconds spent in the air.

So, now we have to include the angle of the trajectory, which complicates matters some.