Will rate, thank you in advance.
Solution :
Given that,
sample size = n =23
Degrees of freedom = df = n - 1 = 23 - 1 = 22
=1-C%=1-.95=0.05
t /2,df = 2.074
Margin of error = E = t/2,df * (s /n)
= 2.074 * (20.7 / 23)
=8.95
The 95% confidence interval estimate of the population mean is,
- E + E
238.1-8.95 238.1+8.95
229.15 247.05
Ansb:
Yes. because a grade of 250 is not in interval
Ansc:
it is not unusual because it is just outside the confidence interval
Will rate, thank you in advance. A consumer organization wants to estimate the actual tread wear...
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