The probability of a missile hitting the target successfully in a trial is 0.2. Five successful hitting are needed to destroy a particular target. What is the probability that the target will be destroyed in the 7th trial?
Probability and statistical analysis
1
$\begingroup$
probability
statistics
-
0My comment [on your other question](http://math.stackexchange.com/q/193073/6179) fully applies. – 2012-09-09
1 Answers
2
So you want the probability of exactly $4$ "successes" in the first $6$ trials, and then a success on the $7$th trial. The probability is $\binom{6}{4}(0.2)^4(0.8)^2(0.2).$
The part before the final $0.2$ is a straight Binomial Distribution calculation.
I prefer problems about picking jelly beans from a large jar.