The credit scores of 35-year-olds applying for a mortgage at Ulysses Mortgage As

Question

The credit scores of 35-year-olds applying for a mortgage at Ulysses Mortgage Associates are normally distributed with a mean of 600 and a standard deviation of 65.

Find the credit score that defines the upper 20 percent. (Use Excel or Appendix C to calculate the z-value. Round your final answer to 2 decimal places.)

Eighty-five percent of the customers will have a credit score higher than what value? (Use Excel or Appendix C for calculation of z-value. Round your final answer to 2 decimal places.)

The credit scores of 35-year-olds applying for a mortgage at Ulysses Mortgage Associates are normally distributed with a mean of 600 and a standard deviation of 65.

Explanation / Answer

a)

P(X >x) = 0.2

=>

P(Z > x-mean/std) = 0.2

=>

x - 600/65 = invnorm(1-0.2) = 0.842

=>

x = 654.73

b)

P(X>x) = 0.85

=>

x-600/65 = invnorm(1-0.85) = -1.036

=>

x = 532.66

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