The average life expectancy of computers produced by Ahmadi, Inc ...

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The average life expectancy of computers produced by Ahmadi, Inc is 6 years with a standard deviation of 10 months. Assume that the lives of computers are normally distributed. Suggestion: For this problem, convert ALL of the units to months.
 a. What is the probability that a randomly selected computer will have a life expectancy of at least 7 years?
  b. Computers that fail in less than 5.5 years will be replaced free of charge. What percentage of computers are expected to be replaced free of charge?
  c. What are the minimum and the maximum life expectancy of the middle 95 of the computers' lives? Give your answers in months and do not round your answers.
  d. The company is expecting that only 104 of this year's production will fail in less than 3 years and 8 months. How many computers were produced this year?

Question 2

The Mathematics part of the SAT scores of students at UTC are normally distributed with a mean of 500 and a standard deviation of 75.
 a. If 2.28 percent of the students who had the highest scores received scholarships, what was the minimum score among those who received scholarships? Do not round your answer.
  b. It is known that 6.3 percent of students who applied to UTC were not accepted. What is the highest score of those who were denied acceptance? Do not round your answer.
  c. What percentage of students had scores between 575 and 650?

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Answer to Question 1

a . 0.1151
b. 27.5
c. Minimum = 52.4 Months Maximum = 91.6 Months
d. 40,000

Answer to Question 2

a . 650
b. 385.25
c. 13.59