Which quadratic equation is equivalent to (x + 2)^2 + 5(x + 2) – 6 = 0? A. (u + 2)^2 + 5(u + 2) – 6 = 0 where u = (x – 2) B. u^2 + 4 + 5u – 6 = 0 where u = (x – 2) C. u^2 + 5u – 6 = 0 where u = (x + 2) D. u^2 + u – 6 = 0 where u = (x + 2) (This is a question from Edg by the way)

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.