Luke is building a storage building and needs to have a slab of concrete poured. He knows the contractor charges an initial cost of $95 plus an additional $3.50 per square foot of concrete. Formulate a function that can be used to determine the cost, in dollars, to pour a concrete slab with an area of x square feet.

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.