The probability of a man hitting a target in one fire is 15. Then the minimum number of fire he must follow in  order to make his chance of hitting the target more than 34is

Probability of hitting the target in one fire, p=15 Then the probability of hitting the target at least once in n fires=1− (probability of not hitting the target) =1−(4/5)n>3/4⇒(4/5)n<1/4⇒ The least value of n is 7