A random sample of 250 physicians shows that there are 40 of them who make at least $400,000 a year. What is the test statistic if we want to test that the true proportion of physicians in the...

A random sample of 250 physicians shows that there are 40 of them who make at least $400,000 a year. What is the test statistic if we want to test that the true proportion of physicians in the population who make at least $400,000 a year is less than 0.20?