Question

The price of a head of iceberg lettuce varies greatly with the season and the geographic location of a store. During February, a researcher contacts a random sample of 39 grocery stores across Canada and asks the produce manager of each to state the current price charged for a head of iceberg lettuce. Using the researcher’s results that follow, construct a 99% confidence interval to estimate the mean price of a head of iceberg lettuce in February in Canada.

$	1.59	$	1.25	$	1.65	$	1.40	$	0.89
	1.19		1.50		1.49		1.30		1.39
	1.29		1.60		0.99		1.29		1.19
	1.20		1.50		1.49		1.29		1.35
	1.4		0.89		1.1		1.49		1.09
	1.50		1.50		1.55		1.20		1.15
	0.99		1.00		1.30		1.25		1.10
	1.00		1.55		1.29		1.39

Answer 1

The sample mean is and the sample standard deviation is s=0.2072902. The size of the sample is n = 39 and the required confidence level is 99%.

The number of degrees of freedom are df = 39 - 1 = 38, and the significance level is α=0.01.

The critical t-value for α=0.01 and df=38 degrees of freedom is tc​=2.712.

The 99% confidence for the population mean μ is computed using the following expression

Therefore, the 99 % confidence for the population mean μ is