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. At Tranquil Island Central School a sample of n = 242 students took the TOEFL test in 2002. Their sample mean was = 467 with a sample standard deviation of sx = 56. Construct a 95% confidence interval for the population mean µ TOEFL score for TICS.
1. __________ What is ?
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 µ?
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/Ön
10. Use - E £ µ £ + E to construct the 95% confidence interval for the population mean µ TOEFL score for TICS.

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