Question

11.17 In a pollution study of the air in a certain downtown area, an EPA technician ob- tained a mean of 2.34 micrograms of suspended benzene-soluble matter per cubic meter with a standard deviation of 0.48 microgram for a sample of size n = 9. As- suming that the population sampled is normal. (a) construct a 95% confidence interval for the mean of the population sampled: (b) what can the technician assert with 99% confidence about the maximum error if x= 2.34 micrograms per cubic meter is used as an estimate of the mean of the population sampled?