Question

A random sample of state gasoline taxes (in cents) is shown here for 12 states. 32.6 35.9 49.3 47.6 53.6 40.1 63.8 39.9 66.1 65.8 55 50.2 Source: http:/www.api.org/statistics/fueltaxes/ Download data Part 1 out of 2 Use the data to estimate the true population mean gasoline tax with 86% confidence. Assume the variable is normally distributed. Round the answers to two decimal places. <u CHECK NEX

Answer 1

Count, N: 12 Sum, Ex: 599.9 Mean, X 49.991666666667 Variance, s2: 131.37537878788 Steps N S = 1 N-1 (Xi – T)? i=1 S2 = (xi - x)2 N-1 (32.6 - 49.991666666667)2 + + (50.2 - 49.991666666667)2 12-1 1445. 1291666667 11 = 131.37537878788 S = V131.37537878788 = 11.461909910127

sample mean 'x̄=	49.992
sample size   n=	12
sample std deviation s=	11.462
std error 'sx=s/√n=	3.3088
for 86% CI; and 11 df, value of t=		1.590630579
margin of error E=t*std error    =		5.263023625
lower bound=sample mean-E =		44.72867638
Upper bound=sample mean+E =		55.25472362
from above 86% confidence interval for population mean =(44.73,55.25)