A 90% confidence interval for the average time spent studying for the final exam

Question

A 90% confidence interval for the average time spent studying for the final exam is (12 hours, 15 hours). A student interpreted the interval as, “We’re 90% confident that 90% of all students studied between 12 and 15 hours for the final exam.” Is this a correct interpretation?

a) Yes.

b) No. A confidence interval gives us a range of possible values for the average in a population and not about the percent of individual observations in the confidence interval.

c) No. A confidence interval gives us a range of possible values for the average in the sample and not about the percent of individual observations in the confidence interval.

d) No. A confidence interval gives us the probability that one individual has a value in the confidence interval and not about the percent of individual observations in the confidence interval.

Explanation / Answer

Confidence Interval
CI = x ± Z a/2 * (sd/ Sqrt(n))
Where,
x = Mean
sd = Standard Deviation
a = 1 - (Confidence Level/100)
Za/2 = Z-table value
CI = Confidence Interval

b) No. A confidence interval gives us a range of possible values for the average in a population and not about the percent of individual observations in the confidence interval.

Related Questions

Navigate

• Browse (All)
• Browse A
• Subjects

Integrity-first tutoring: explanations and feedback only — we do not complete graded work. Learn more.