Quiz 5 (2) - d Within 1.5 standard deviations of the mean(1...

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BA 240 W. Li Score: ____of 10 QUIZ 5 Show your work CLEARLY and COMPLETELY! Name: _________________________ Draw the Normal Curves, highlight the corresponding areas! Round to SECOND Digits after Decimal Point for Z-scores Keep the Original FOUR digits after the Decimal Point for Probability Problem 1 : Stanford-Binet IQ Test scores are normally distributed with a mean score of 100 and a standard deviation of 16. Find the probability that a randomly selected person has an IQ test score a) Over 140. (2 points) z-score of 140 = P(X > 140) = b) Under 88. (2 points) z-score of 88 = P(X < 88) = c) Between 72 and 128. (3 points) z-score of 72 = z-score of 128 = P(72 < X < 128) =
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Unformatted text preview: d) Within 1.5 standard deviations of the mean. (1 point) Problem 2 : A tire company has developed a new type of steel-belted radial tire. Extensive testing indicates the population of mileages obtained by all tires of this new type is normally distributed with a mean of 40,000 miles and a standard deviation of 4,000 miles. The company wishes to offer a guarantee providing a discount on a new set of tires if the original tires purchased qualify the guarantee mileage. What should the guaranteed mileage be if the tire company desires that no more than 2 percent of the tires will fail to meet the guaranteed mileage? (2 points) z-score = X =...
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