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  1. Solved (Free): A western city has 18 police officers eligible for promotion. Eleven of the 18 are Hispanic
    A western city has 18 police officers eligible for promotion. Eleven of the 18 are Hispanic. Suppose only five of the police officers are chosen for promotion and that one is Hispanic. If the officers chosen for promotion had been...
  2. Solved (Free): Random samples of households were selected from each of three regions in a large metropolitan area. The number of households selected from
    Random samples of households were selected from each of three regions in a large metropolitan area. The number of households selected from each region and the corresponding mean household incomes are provided in the table below. Region Households Selected (Number)...
  3. Solved (Free): Earnings by gender According to the 2005 American Community Survey taken by the U.S. Bureau of the Census, the median earnings in the past
    Earnings by gender According to the 2005 American Community Survey taken by the U.S. Bureau of the Census, the median earnings in the past 12 months was \$32,168 for females and \$41,965 for males, whereas the mean was \$39,890 for...
  4. Solved (Free): In a history class there are 25 freshman, 21 sophomores, and 18 juniors. If the freshman averaged 81 on an examination, the sophomores averaged 84
    In a history class there are 25 freshman, 21 sophomores, and 18 juniors. If the freshman averaged 81 on an examination, the sophomores averaged 84, and the juniors averaged 72, find the mean grade for the entire class. (round to...
  5. Solved:The first assignment in a statistical computing class involves running a short program. If past experience indicates
    The first assignment in a statistical computing class involves running a short program. If past experience indicates that 40% of all students will make no programming errors, compute the (approximate) probability that in a class of 50 students a. At...
  6. Solved (Free): False-positives in testing for HIV. A rapid test for the presence in the blood of antibodies to HIV, the virus that causes
    False-positives in testing for HIV. A rapid test for the presence in the blood of antibodies to HIV, the virus that causes AIDS, gives a positive result with probability about 0.004 when a person who is free of HIV antibodies...
  7. Solved: A pharmacist receives a shipment of 23 bottles of a drug and has 3 of the bottles tested. If 6 of the 23 bottles are con
    A pharmacist receives a shipment of 23 bottles of a drug and has 3 of the bottles tested. If 6 of the 23 bottles are contaminated, what is the probability that less than 2 of the tested bottles are contaminated?...
  8. Solved (Free): In the United States, 44% of the population has type O blood. Suppose a random sample of 12 persons is taken
    In the United States, 44% of the population has type O blood. Suppose a random sample of 12 persons is taken. Find the probability that at most 6 of the persons will have type O blood by using the normal...
  9. Solved: The amount of time that a union stays on strike is judged to follow an exponential distribution with a mean
    The amount of time that a union stays on strike is judged to follow an exponential distribution with a mean of 10 days. a. Find the probability that a strike lasts less than one day. b. Find the probability that...
  10. Solved (Free): Number skills of young men. Suppose that scores of men aged 21 to 25 years on the quantitative part of the National Assessment of Education Progress
    Number skills of young men. Suppose that scores of men aged 21 to 25 years on the quantitative part of the National Assessment of Education Progress (NAEP) test follow a Normal distribution with standard deviation $\sigma= 60$. You want to...