Q1) A sample of 23 European countries found that variance of life expectancy was 7.3 years. Determine the 95% confidence interval estimate for variance of life expectancy in Europe?
a) 27.2 < σσ^{2} < 118.3
b) 5.6 < σ^{2} < 10.3
c) 4.4 < σ^{2} < 14.6
d) 28.9 < σ^{2} < 115.0
Q2) Determine the 95% confidence interval for standard deviation of lengths of pipes if sample of 26 pipes has standard deviation of 10 inches.
a) 14.0 < σ < 16.0
b) 7.8 < σ < 13.8
c) 74.0 < σ < 126.0
d) 60.8 < σ < 190.5
Q3) Average gas mileage of certain model car is 26 miles per gallon. If gas mileages are normally distributed with standard deviation of 1.3, determine the probability that randomly selected car of this model has gas mileage between 25.8 and 26.3 miles per gallon.
a) 0.15
b) 0.85
c) 0.70
d) 0.30
Q4) At large department store, average number of years of employment for cashier is 5.7 with standard deviation of 1.8 years. If number of years of employment at this department store is normally distributed, determine the probability that cashier chosen at random has worked at the store for over 10 years?
a) 0.4916
b) 0.9916
c) 0.0084
d) 0.0054
Q5) To be accepted into top university, applicants should score within top 5% on the SAT exam. Given that SAT test scores are normally distributed with mean of 1000 and standard deviation of 200, compute the lowest possible score a student needs to qualify for acceptance into the university?
a) 1330
b) 1400
c) 1250
d) 1100