Which relation is not a function? Please justify your answer. A. yes because the number of x-values is the same as the number of y-values.
B. yes because every X- and y-value is positive.
C. yes because every X-Value corresponds a single y-value
D. No because two points with the same y-value have different x-values.
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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.