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Find a z-score such that the probability of getting a z less than that value is .654.

Find a z-score such that the probability of getting a z less than that value is .654. Two out of five adult smokers acquired the habit by age 14. A survey of 1000 randomly selected smokers is conducted. Would it be unusual to have more than 476 of them acquire the habit by age 14?.

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Find a z-score such that the probability of getting a z less than that value is .654.

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  1. Find a z-score such that the probability of getting a z less than that value is .654.

  2. Two out of five adult smokers acquired the habit by age 14. A survey of 1000 randomly selected smokers is conducted. Would it be unusual to have more than 476 of them acquire the habit by age 14?

  3. A recent study of the life span of TI-84 calculators found the average life span to be 3.1 years with a standard deviation of 0.9 years. (assume that these are known to be population values. • a. Would it be unlikely to have a TI-84 last 4 years? • b. Would it be unlikely for the mean of 10 calculators life span to exceed 4 years?

  4. John scored in the 93rd percentile on his admissions test to law school. Unfortunately John has no idea what that means. You have been asked to enlighten him. What will you tell John?

  5. If 10 percent of the population is left handed, • A. What is the probability of randomly selecting 3 people who are all left handed. • B. What is the probability of getting at least 2 left handed people out of a random sample of 10?

  6. A statistics quiz consists of 10 multiple choice questions, with five possible answers for each. What is the probability if a person guesses for all questions that that individual will get at least a 40%?

  7. The lengths of pregnancies are normally distributed with a mean of 268 days and a standard deviation of 15 days. (Assume that these are population values) On June 16 a hospital had 12 babies born. What is the probability that the mean length of pregnancy was 263 days or less?

  8. A machine is designed to fill jars with 16 ounces of coffee. A consumer claims that the machine in not filling the jars completely full. A sample of 8 jars has a mean of 15.6 ounces and a standard deviation of .3 ounces. Is there enough evidence to support the consumer’s claim at the 90% certainty level?

  9. A recent internet survey asked users of the lose-a-lot diet program if it worked. Twenty people responded and 123% said that they lost more weight than with other diet programs. • Comment

  10. One thousand tickets are sold a $1 each for four prizes of $100, $50, $25, and $10. After each drawing, the winning ticket is then returned to the pool of tickets. What is the expected value if a person purchases two tickets?

  11. In a recent survey of 150 households, 54 had central air conditioning. Find and interpret 90% confidence intervals.

  12. The Data shown represent the number of hours that 12 part time employees at a toy store worked during the weeks before and after Christmas. Compare the distributions using box plots. Min max Q1 Q2 Q3 • Before 12 38 21 30 33.5 • After 12 32 14.5 18 23

  13. The ages of the US presidents at the time of inauguration are as follows • 42 42 46 46 47 48 49 49 50 • 50 51 51 51 52 52 54 54 54 • 54 54 55 55 55 55 56 56 56 • 57 57 57 57 58 60 61 61 61 • 62 64 64 65 68 69 • Mean is 54.9 and std. dev is 6.3 years. Would you say the data are approximately normal?

  14. Hospital records indicate that maternity patients stayed in the hospital for the number of days shown in the distribution Days freq 3 15 4 32 5 56 6 19 7 5 What is the probability a patient stayed 5 days? At most 4 days? At least 5 days? Less than 6 days?

  15. The population mean number of students in a public elementary school is 458 and the population standard deviation is 97. If a random sample of 36 public elementary schools is selected, find the probability that the number of students enrolled is between 450 and 470. What is the probability that one school will have between 450 and 470 students?

  16. A jar has 3 yellow balls, 4 red balls, 5 green balls and 2 pink balls. If you draw three balls from the jar without replacement, what is the probability that they will all be pink.

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