Question

Suppose the mean cholesterol levels of women age 45-59 is 5.3 mmol/l and the standard deviation is 1.1 mmol/l. Assume that cholesterol levels are normally distributed.

State the random variable.

• The standard deviation of cholesterol levels of women age 45-49.
• The mean cholesterol level of women age 45-49.
• The cholesterol level of a woman age 45-49.

Find the probability that a woman age 45-59 has a cholesterol level above 6.5 mmol/l (considered a high level). Round to four decimal places.
P(x > 6.5) =

Suppose doctors decide to test the woman’s cholesterol level again and average the two values. Find the probability that this woman’s mean cholesterol level for the two tests is above 6.5 mmol/l. Round to four decimal places.
P(x̄ > 6.5) =

Suppose doctors being very conservative decide to test the woman’s cholesterol level a third time and average the three values. Find the probability that this woman’s mean cholesterol level for the three tests is above 6.5 mmol/l. Round to four decimal places.
P(x̄ > 6.5) =

If the sample mean cholesterol level for this woman after three tests is above 6.5 mmol/l, what could you conclude?

• If the woman's three cholesterol tests have a mean above 6.5 mmol/l, there is not enough evidence to conclude that she has high cholesterol.
• If the woman's three cholesterol tests have a mean above 6.5 mmol/l, then you may want to conclude that she has high cholesterol.

Answer 1