Question

CNNBC recently reported that the mean annual cost of auto insurance is 995 dollars. Assume the standard deviation is 295 dollars, and the cost is normally distributed. You take a simple random sample of 13 auto insurance policies. Round your answers to 4 decimal places.

1. What is the distribution of XX? XX ~ N(,)
2. What is the distribution of ¯xx¯? ¯xx¯ ~ N(,)
3. What is the probability that one randomly selected auto insurance is less than $1019?
4. a simple random sample of 13 auto insurance policies, find the probability that the average cost is less than $1019.
5. For part d), is the assumption of normal necessary?

Answer 1