Elspeth knows that Pi times r almost-equals 9.42 centimeters. What would she need to do to find the circumference? She could multiply 9.42 by 2.
She could multiply 9.42 by Pi.
She could divide 9.42 by 2 to find the radius, and then square the radius.
She could divide 9.42 by Pi to find the radius, and then multiply 9.42 by the radius.

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.