PLEASE HELP MIDDLE SCHOOL MATH

Hi, can anyone show me how to do this problem? 100 points for this. in advance

Which is the solution to the inequality? 2 3/52 1/15 b< 3 2/15 b> 3 2/15

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.