SOLUTION: Assume credit ratings are normally distributed with a mean of 250 and a standard deviation of 40. If a person is randomly selected find the probability that his credit rating is be

Question 715534: Assume credit ratings are normally distributed with a mean of 250 and a standard deviation of 40. If a person is randomly selected find the probability that his credit rating is between 220 and 290
Answer by stanbon(75887) (Show Source): You can put this solution on YOUR website!
Assume credit ratings are normally distributed with a mean of 250 and a standard deviation of 40. If a person is randomly selected find the probability that his credit rating is between 220 and 290
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z(220) = (220-250)/40 = -30/40 = -3/4
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z(290) (290-250)/40 = 40/40 = 1
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P(220 < x < 290)
= P(-3/4 < z < 1)
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At this point you need a z-chart or calculator or
other software to find the answer.
I used my TI-84 calculator to get = normalcdf(-3/4,1) = 0.6147
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Cheers,
Stan H.
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