How many close friends do you have? Supose that the number of close friends adul

Question

How many close friends do you have? Supose that the number of close friends adults claim to have varies from person to person with mean = 9 and standard deviation = 2.5.  An option poll asks this question of SRS of 1100 adults.  We see later that in this situation the sample mean respone x-bar has approximatley the Normal distrubiton with mean 9 and standard devaiton 0.075.  What is P( 8.9 less then or equeal to x-bar less than or equal to 9.1), the probibiltiy that the sample result x-bar estimates the population truth = 9 to within plus or minus 0.1?

Explanation / Answer

+ or - .1 means a z score of .1/0.075 or + or - 1.33. If you check a z (normal) table the probability of a z score within 1.33 standard deviations of the mean is 0.8164.

Related Questions

Navigate

• Browse (All)
• Browse H
• Subjects

---

---

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