SOLUTION: Because of the relatively high interest rates, most consumers attempt to pay off their credit card bills promptly. However, this is not always possible. An analysis of the amount o

Algebra ->  Probability-and-statistics -> SOLUTION: Because of the relatively high interest rates, most consumers attempt to pay off their credit card bills promptly. However, this is not always possible. An analysis of the amount o      Log On


   

Question 428590: Because of the relatively high interest rates, most consumers attempt to pay off their credit card bills promptly. However, this is not always possible. An analysis of the amount of interest paid monthly by a bank's Visa cardholders reveals that the amount is normally distributed with a mean of 29 dollars and a standard deviation of 6 dollars.
What interest payment is exceeded by only 21% of the bank's Visa cardholders??
Answer by stanbon(75887) About Me  (Show Source):
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Because of the relatively high interest rates, most consumers attempt to pay off their credit card bills promptly. However, this is not always possible. An analysis of the amount of interest paid monthly by a bank's Visa cardholders reveals that the amount is normally distributed with a mean of 29 dollars and a standard deviation of 6 dollars.
What interest payment is exceeded by only 21% of the bank's Visa cardholders??
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Draw the picture of a normal curve with mean = 29
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Find the z-value with a right-tail of 0.21
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invNorm(0.79) = 0.8064
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Find the corresponding payment:
x = zs+u
x = 0.8064*6+29
x = $33.84
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Cheers,
Stan H.
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