Supposexhas a normal distribution withs=1.5. A random sample of size66has a sample mean ofx= 20.

(a) What conditions are necessary for your calculations? (Select all that apply.)

• is unknown
• is known
• normal distribution ofx
• uniform distribution ofx

(b) Find a 95% confidence interval for mu. What is the margin of error? (Round your answers to two decimal places.)

• lower limit=
• upper limit=
• margin of error=

(c) Interpret your results in the context of this problem.

• 1. There is a 95% chance that the interval is one of the intervals containing the true average.
• 2. The probability that this interval contains the true average is 0.95.
• 3. The probability that this interval contains the true average is 0.05.
• 4. There is a 5% chance that the interval is one of the intervals containing the true average.