Recycled cds, incorporated, offers a choice of 5 used cds for $24, with each additional cd costing $7. write a cost function for purchasing 5 or more cds. what will the cost of buying 12 cds be? let x represent the number of cds over 5.

Arandom sample of n = 25 observations is taken from a n(µ, σ ) population. a 95% confidence interval for µ was calculated to be (42.16, 57.84). the researcher feels that this interval is too wide. you want to reduce the interval to a width at most 12 units. a) for a confidence level of 95%, calculate the smallest sample size needed. b) for a sample size fixed at n = 25, calculate the largest confidence level 100(1 − α)% needed.