Suppose that a simple random sample is taken from a normal population having a standard deviation of 11 for the purpose of obtaining a 90% confidence interval for the mean of the population. Complete parts (a) through (c) below.
a. If the sample size is 9, obtain the margin of error.
The margin of error for a sample size of 9 is ___________
(Round to two decimal places as needed.)
b. Repeat part (a) for a sample size of 36.
The margin of error for a sample size of 36 is _________
(Round to two decimal places as needed.)
c. Can you guess the margin of error for a sample size of 144?
Explain your reasoning.
The margin of error for a sample size of 144 is _______________.
(Round to two decimal places as needed.)
Explain your reasoning.
Because the sample size _____________ (decreased, increased) by a factor of
___________ from part (b) to part (c), the margin of error was __________ (divided, multiplied) by ___________ (Type whole numbers.)