The proportion of left-handed people in the general population is about 0.1. Suppose a random sample of 225 people is observed.
a. Since the sample proportion has a normal distribution, its values follow the Standard Deviation Rule. What interval is almost certain (probability .997) to contain the sample proportion of left-handed people?
b. In a sample of 225 people, would it be unusual to find that 40 people in the sample are left-handed?