Question

6. An airline is interested in estimating the mean number of unoccupied seats per flight over the past year. They randomly select 250 flights and count the number of unoccupied seats per flight. The sample mean is 12.2 seats with a sample standard deviation of 3.5 seats. Based on previous studies they know that the population standard deviation is 3.6 seats. (a) Find each of the following quantities. • i= .0= s = n= (b) Use the following steps to construct a 96% confidence interval for the population mean number of vacant seats per flight. • Does this problem require a normal distribution, or should you use Student's t-distribution? Explain. • Write a formula for EBM, and then find EBM. Draw a graph if that will help explain any part of your calculation. • Write a formula for the the confidence interval and then write the confidence interval. (c) If the airline wants to increase the confidence level to 98% while keeping the same error bound, how must they adjust their sampling procedure? Be specific.

Answer 1

12.2. a ) 2 3-6 S: 3.5 n: 250 16) 967. (-4) 100%; 9.8%. Ind:0.96 di 1-0.96 0.04. ?d/2 et 2212 Vn 3:06 12-2 + 2.06 Vaso normal distribution is o we ard dising Known. 2 0.4690 # E13m : 2.06 x 36 V250 & confidence interval formula X = € - E 12.2 - 6-4690: Jl731 > Lowen bound: appen bound: att 12.2 +0:4690. 12.669. (1.731. { Mi-M, < 12-669

2-33 ( ) 2012 98% 366 06505 0.5305 EBM :: 29.338 250 confi ali dence intenval x & GBM 12.2 t 0.5305 ( 12.2 - 0.5305) (MAMA 12:2 +015305 11. 669.5 to 127305