Suppose a travel industry research company takes a random sample of 22 business travels in the financial industry and determine that the sample average cost of the domestic trip is $1250 and standard deviation of $279. Construct a 98% confidence interval for the population mean from these sample data.

b) A random sample of 200 physicians shows that there are 36 of them who make at least $400,000 a year. Can we conclude at the 1% significance level that the true proportion of physicians in the population who make at least $400,000 a year is less than 0.24?