Events a and b are overlapping. p(a) = 6/17 ; p(b) = 5/17 ; p(a and b) = 3/17 . find p(a or b). (paypal for $50 if you answer my next question after this)

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.