A company claims that the mean monthly residential electricity consumption in a certain region is more than 870 kilo Watt-hours (kWh). You want to test this claim. You find that a random sample of 69 residential customers has a mean monthly consumption of 910 kWh. Assume the population standard deviation is 120 kWh. At alpha αequals=0.10 can you support the claim? Complete parts (a) through (e).
| null hypothesis:Ho μ | <= | 870 | |
| Alternate Hypothesis:Ha μ | > | 870 | |
| for 0.1 level with right tail test , critical z= | 1.28 | ||
| Decision rule:reject Ho if test statistic z>1.28 | |||
| population mean μ= | 870 | ||
| sample mean 'x̄= | 910.000 | ||
| sample size n= | 69.00 | ||
| std deviation σ= | 120.000 | ||
| std error ='σx=σ/√n= | 14.4463 | ||
| test stat z = '(x̄-μ)*√n/σ= | 2.77 | ||
| p value = | 0.0028 | ||
since p value <0.10 ; we reject null hypothesis
we have sufficient evidence to support the claim
Get Answers For Free
Most questions answered within 1 hours.