SOLUTION: 5. Diastolic blood pressures are assumed to follow a normal distribution with a mean of 85 and a standard deviation of 12 a. What proportion of people have disastolic blood pr

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Question 304719: 5. Diastolic blood pressures are assumed to follow a normal distribution with a mean of 85 and a standard deviation of 12
a. What proportion of people have disastolic blood pressure less than 90%

b. What proportion have diatolic blood pressure between 80 and 90% ?

Answer by stanbon(75887) (Show Source):
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Diastolic blood pressures are assumed to follow a normal distribution with a mean of 85 and a standard deviation of 12
a. What proportion of people have disastolic blood pressure less than 90%
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z(90) = (90-85)/12 = 0.4167
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P(x < 90) = P(z < 0.4167) = 0.6616
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b. What proportion have diatolic blood pressure between 80 and 90% ?
80 is 5 to the left of the mean just as 90 is 5 to the right.
P(80< x < 90) = P(-0.4167 < z < 0.4167) = 0.3231
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Cheers,
Stan H.
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