The Inconvenient Light Company advertises that, on average, its CFL (Compact Fluorescent Light) bulbs last more than 4600 hours. To test this claim using a 2% significance level, a statistician plans to take a random sample of 97 bulbs and measure the amount of time until each bulb fails. The lifetimes of the 97 bulbs in the sample had a mean of 4656 hours and a standard deviation of 490 hours. The value of the test statistic for this sample is
Solution :
= 4600
= 4656
s = 490
n = 97
This is the right tailed test .
The null and alternative hypothesis is ,
H0 : = 4600
Ha : > 4600
Test statistic = t
= ( - ) / s/ n
= (4656 - 4600) /490 / 97
= 1.123
p(Z >1.126 ) = 1-P (Z < 1.126) = 0.1316
P-value = 0.1316
= 0.02
p=0.1316 ≥ 0.02
Fail to reject the null hypothesis
There is not enough evidence to claim that the population mean μ is greater than 4600, at the 0.02 significance level.
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