You can
put this solution on YOUR website! Mr. Butts smoked 15 cigarettes per day. Whats the probability a smoker will smoke less than Mr. Butts. mean = 11. standard deviation = 5
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z(15) = (15-11)/5 = 0.8
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P(x<15) = P(z<0.8) = 0.7881
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Cheers,
Stan H.