### MS 150 Stat 2002 Spring Quiz 06

- 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?

- Why?

- 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.
- __________ What is ?
- __________ What is sx?
- __________ What is n?
- __________ What is c?
- __________ Is n >= 30?
- __________ Based on the above, can we use the normal distribution to construct our confidence interval for µ?
- __________ Use z
_{c} = NORMSINV((1-c)/2) to find the negative z-critical value.
- __________ What is the positive value for z
_{c}?
- __________ Calculate the Error E using E = z
_{c}*sx/Ön
- Use - E £ µ £ + E to construct the 95% confidence interval for the population mean µ TOEFL score for TICS.

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