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Which of the following is most likely the next step in the series? a3z, b6y, c9x, d12w, е15v, f18u

Monthly water bills for a city have a mean of $108.43 and a standard deviation of $32.09. find the probability that a randomly selected bill will have an amount greater than $155, which the city believes might indicate that someone is wasting water. would a bill that size be considered unusual?

Name each raycalculation tip: in ray "ab", a is the endpoint of the ray.