Well you know the probability and number or trials (n), so it's just a case of using the binomial distribution formula to calculate P(X=9) + P(X=10) + P(X=11). Are you able to find the answer now?
here is another one...will appreciate any help ...
A recent article in the paper claims that business ethics are at an all-time low. reporting on a recent sample, the paper claims that 30% of all employees believe their company CEO has low ethical standards. Suppose 20 of a company's employees are randomly sampled. Assuming the paper's claim is correct, find the probability that more than 8 but fewer than 12 of the 20 sampled believe the company's CEO has low standards.
The probability of successes out of is
You need to calculate this probability when and and in turn, and add these three results together.
If my working is correct, the answer is 0.1082 (4 d.p.)