Question

The PC Magazine shows that the mean price for liquid crystal display (LCD) computer monitors is $200 with a standard deviation of $30. If 9 LCD computer monitors are randomly selected, then the distribution of the sample mean price is

		Exactly normal with mean $200 and standard deviation $30.
		Exactly normal with mean $200 and standard deviation $10.
		Approximately normal with mean $200 and standard deviation $10.
		Can't be determined without more information

Answer 1

Solution

Here option (4) is correct.

Given mean price of LCD =200

Standard deviation =30

A random sample of size n= 9 is selected.

Since sample size is very small and distribution of population is unknown , we can’t apply CENTRAL LIMIT THEOREM.Without knowing distribution of parent populatian and n is large then only we can say the distribution of sample mean is normally distributed by CLT. Otherwise the parent population should be normal.

Hence we can’t determine the distribution of sample mean with the given condition.