Mark the correct alternative in the following:

A rifleman is firing at a distant target and has only 10% chance o hitting it. The least number of rounds, he must fire in order to have more than 50% chance of hitting it at least once is


Chances of hitting a target in a trial=10%=

Chances of not hitting the target = 90%=

Total probability = 50%=5

Let number of trials=n

So number of trials missed=n-1 to hit on nth trial

Total probability

= 5

Take log on both sides



So one must hit it seven times.