Probability - Binomial Distribution
It has been found that 80% of all printers used operate correctly at the time of installation. A seller sells 10 units during a month.
1)find the prob.that at least 9 of the printers operate correctly at the time of installation.
2)Consider 5 months in which 10 units are sold per month. What is the prob.that at least 9 units operate correctly in each of the 5 months
For 1st part :
Let p(o)=probability that a given printers operates correctly
So we have to find p(o>=9) here.
I understand that for the first part we have use Binomial distribution
But how do we solve the 2nd part?