1. Find out the mean and standard deviation of following probability distribution
| x |
1 |
2 |
3 |
| P(x) |
0.4 |
0.15 |
0.35 |
2. In testing new drug, researchers found that 5% of all patients by using it will have the mild side effect. A random sample of 15 patients by using the drug is selected. Find out the probability that:
a) exactly three will have this mild side effect
b) at least two will have this mild side effect.