Question

please help me I've waited for hours

The average price of a gallon of unleaded regular gasoline was reported to be $2.34 in northern Kentucky (The Cincinnati Enquirer, January 21, 2006). Use this price as the population mean, and assume the population standard deviation is $.20.

1. What is the probability that the mean price for a sample of 30 service stations is within $.03 of the population mean (to 4 decimals)?


2. What is the probability that the mean price for a sample of 50 service stations is within $.03 of the population mean (to 4 decimals)?


3. What is the probability that the mean price for a sample of 100 service stations is within $.03 of the population mean (to 4 decimals)?


4. Calculate the sample size necessary to guarantee at least .95 probability that the sample mean is within $.03 of the population mean (0 decimals).

Answer 1

# What is the probability that the mean price for a sample of 30 service stations is within $.03 of the population mean (to 4 decimals)?
.5878

# What is the probability that the mean price for a sample of 50 service stations is within $.03 of the population mean (to 4 decimals)?
.7108

# What is the probability that the mean price for a sample of 100 service stations is within $.03 of the population mean (to 4 decimals)?
.8664

# Calculate the sample size necessary to guarantee at least .95 probability that the sample mean is within $.03 of the population mean (0 decimals).
?

Answer 2

What is the probability that the mean price for a sample of 30 service stations is within $.03 of the population mean (to 4 decimals)?
.5878

# What is the probability that the mean price for a sample of 50 service stations is within $.03 of the population mean (to 4 decimals)?
.7108

# What is the probability that the mean price for a sample of 100 service stations is within $.03 of the population mean (to 4 decimals)?
.8664

# Calculate the sample size necessary to guarantee at least .95 probability that the sample mean is within $.03 of the population mean (0 decimals).
?