# A hunter uses a laser range finder to find out the distance to his target. If it takes 5.4*10^-7 seconds for the light beam to return to the rangefinder after the hunter turns it on, how far away is the deer?

$81 m$
The velocity of light in air is about $3 \times {10}^{8} \text{m/s}$
Hence by this time the distance travelled by light is: $162 m$
So the distance is: $\frac{162}{2} m = 81 m$