average age

  

The average age of amtrak cars is 20 years. If the distribution of age is normally distributed and 22% of the cars are older than 23 years, find the standard deviation (σ).2. Given n = 36, x̅ = 211, σ = 23, compute a 96% confidence interval (C.I.) for μ.3. Use the binomial probability formula (not the binomial probability distribution table in the appendix) to find the probability of getting 2 or 3 correct responses among 6 different requests from AT&T assistance. AT&T assures us that they are correct 91% of the time.4. Rita is playing Monopoly with her very best friend Cher. On her next move, Rita must throw a sum bigger than 8 on her two dice in order to land on her own property and pass “Go”. What is the probability that she will roll a sum larger than 8?5. The owner of Jim’s Gas Station wishes to determine the proportion of customers who use a credit card to pay at the pump. He surveys 100 customers and finds that 75 paid at pump. Develop a 90% C.I. for the population proportion.