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The random variable X is normally distributed with a mean of 70 and a standard deviation of 10. What is the probability that X is between 72 and 84? (a) 0.683 (b) 0.954 (c) 0.271 (d) 0.340 |
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Answer» (d) 0.340 µ = 70, σ = 10 P(72 < X < 84) = P((72 - 70)/10 < Z < (84 - 70)/10) = P(0.2 < Z < 1.4) = P(0 < Z < 1.4) – P(0 < Z < 0.2) = 0.4192 – 0.0793 = 0.3399 = 0.340 |
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