According to the Organization for Economic Co-operation and Development (OECD), the mean density of physicians per 1000 people worldwide is 3.2.41 A random sample of countries was obtained and the...

According to the Organization for Economic Co-operation and Development (OECD), the mean density of physicians per 1000 people worldwide is 3.2.41 A random sample of countries was obtained and the physician density per 1000 people was recorded for each. The data are given in the following table.

Over time, certain metabolic changes can cause the lens of the eye to become opaque, which leads to loss of vision. In this case, many adults elect to have cataract surgery in which the natural lens of the eye is removed and an artificial lens implant is inserted. A random sample of cataract surgeries was obtained and the length of each surgery was recorded (in hours).42 Past records indicate that the mean time for this type of surgery is 0.75 hour. Assume the underlying population is normal.