A random sample of n=400 students is selected from a population of N=4000 students to...
abondantQ
Answered question
2021-03-05
A random sample of students is selected from a population of students to estimate the average weight of the students. The sample mean and sample variance are found to be confident interval.
Answer & Explanation
liannemdh
Skilled2021-03-06Added 106 answers
Step 1
The confidence interval formula for the population mean when population standard deviation is not known, is defined as follows:
is the critical value of the t-distribution with degrees of freedom of above which, proportion of the observations lie, and below which, proportion of the observation lie, is the sample mean, s is the sample standard deiation, and n is the sample size.
Step 2
The sample mean is , and the sample standard deviation is .
The sample size is . The degrees of freedom is
The confidence level is 0.95. Hence, the level of significance is
Using Excel formula: , the critical value is,
Thus,
Thus, the required confidence interval is (138.53 lb, 141.47 lb).