MS 150 Stat 2002 Spring Quiz 06

  1. In statistics, can you construct a range (a confidence interval) from a sample mean, sample standard deviation, and sample size that will alway include the population mean?

  2. Why?


  3. 95% confidence interval centered on 467At Tranquil Island Central School a sample of n = 242 students took the TOEFL test in 2002. Their sample mean was sample mean xbar = 467 with a sample standard deviation of sx = 56. Construct a 95% confidence interval for the population mean TOEFL score for TICS.
    1. __________ What is sample mean xbar?
    2. __________ What is sx?
    3. __________ What is n?
    4. __________ What is c?
    5. __________ Is n >= 30?
    6. __________ Based on the above, can we use the normal distribution to construct our confidence interval for ?
    7. __________ Use zc = NORMSINV((1-c)/2) to find the negative z-critical value.
    8. __________ What is the positive value for zc?
    9. __________ Calculate the Error E using E = zc*sx/n
    10. Use sample mean xbar - E sample mean xbar + E to construct the 95% confidence interval for the population mean TOEFL score for TICS.

      ___________ ___________
    11. Is the TICS 2001 TOEFL score of 477 within the 2002 confidence interval?