Since in this case we are
only using the variance of the sample and not the variance of the real population,
therefore we use the t statistic. The formula for the confidence interval is:
<span>CI = X ± t * s / sqrt(n) ---> 1</span>
Where,
X = the sample mean = 84
t = the t score which is
obtained in the standard distribution tables at 95% confidence level
s = sample variance = 12.25
n = number of samples = 49
From the table at 95%
confidence interval and degrees of freedom of 48 (DOF = n -1), the value of t
is around:
t = 1.68
Therefore substituting the
given values to equation 1:
CI = 84 ± 1.68 * 12.25 /
sqrt(49)
CI = 84 ± 2.94
CI = 81.06, 86.94
<span>Therefore at 95% confidence
level, the scores is from 81 to 87.</span>
Answer:
0
Step-by-step explanation:
because
k c r
10 + (-10)
10 - 10=0
Answer:
15000
Step-by-step explanation:
Given that a professor wants to know how undergraduate students at X University feel about food services on campus, in general. She obtains a list of email addresses of all 15,000 registered undergraduates from the registrar’s office and mails a questionnaire to 300 students selected at random.
Only 150 questionnaires are returned.
So the sample size changed to 150. But population is the number of registered undergraduates which do not change.
Population size = 15000
Step-by-step explanation:
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