Among a sample of 100 students selected at random from one college,the mean number of siblings is 1.4 with a standard deviation of 1.3.Find a 95% confidence interval for the mean number of siblings for all students at this college.

A) (1.08,1.73)
B) (1.36,1.44)
C) (61.8,66.2)
D) (1.15,1.65)
E) (1.24,1.44)

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Magdalena Schoe · Accepted Answer

Final Answer : D, Explanation :  The correct answer is D.The formula for a 95% confidence interval for the mean is:mean +/- 1.96 * (standard deviation / square root of sample size)Plugging in the values we have:1.4 +/- 1.96 * (1.3 / square root of 100)= 1.4 +/- 1.96 * (1.3 / 10)= 1.4 +/- 1.96 * 0.13= 1.4 +/- 0.25= (1.15, 1.65)

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