Bob Nale is the owner of Nale\'s Quick Fill. Bob would like to estimate the mean
ID: 3384988 • Letter: B
Question
Bob Nale is the owner of Nale's Quick Fill. Bob would like to estimate the mean number of gallons of gasoline sold to his customers. Assume the number of gallons sold follows the normal distribution with a population standard deviation of 2.1 gallons. From his records, he selects a random sample of 58 sales and finds the mean number of gallons sold is 8.36. (Round your answers to 2 decimal places.)
The 99 percent confidence interval for the population mean is between and .
Bob Nale is the owner of Nale's Quick Fill. Bob would like to estimate the mean number of gallons of gasoline sold to his customers. Assume the number of gallons sold follows the normal distribution with a population standard deviation of 2.1 gallons. From his records, he selects a random sample of 58 sales and finds the mean number of gallons sold is 8.36. (Round your answers to 2 decimal places.)
Explanation / Answer
a)
Point f estimate = 8.36
b)
CI = x ± Z a/2 * (sd/ Sqrt(n))
Where,
x = Mean
sd = Standard Deviation
a = 1 - (Confidence Level/100)
Za/2 = Z-table value
CI = Confidence Interval
Mean(x)=8.36
Standard deviation( sd )=2.1
Sample Size(n)=58
Confidence Interval = [ 8.36 ± Z a/2 ( 2.1/ Sqrt ( 58) ) ]
= [ 8.36 - 2.58 * (0.276) , 8.36 + 2.58 * (0.276) ]
= [ 7.649,9.071 ]