MA 260 MA260 STATISTICAL ANALYSIS I EXAM 6 ANSWERS (2021) - ASHWORTH
Ashworth MA260 Statistical Analysis I Exam 6 Answers (2021)
1. The weights of 6-week-old poults (juvenile turkeys) are normally distributed with a mean 9.0 pounds and standard deviation 2.5 pound(s). Find the 75th percentile of the weights.
2. Find the shaded area under the standard normal curve.
3. The mean number of pets per household is 3.33 with standard deviation 1.6. A sample of 53 households is drawn. Find the 78th percentile of the sample mean.
4. A survey reported that in a recent year, the mean serum cholesterol level in milligrams per deciliter for U.S. adults was 199 with a standard deviation of 44. A random sample of 104 adults was chosen. What is the probability that the mean cholesterol level is less than 198?
5. Use technology to solve the following problem: The lifetime of a certain type of automobile tire (in thousands of miles) is normally distributed with mean μ = 40 and standard deviation σ = 6. What proportion of tires have lifetimes greater than 32 thousand miles?
6. Use the normal approximation to find the indicated probability. The sample size is n, the population proportion of successes is p, and X is the number of successes in the sample.
7. Use technology to solve the following problem: A ferry will safely accommodate 79 tons of passenger cars. Assume that the mean weight of a passenger car is 1.9 tons with standard deviation 0.5 tons. If a random sample of 39 cars are loaded onto the ferry, what is the probability that the maximum safe weight will be exceeded?
8. A gardener buys a package of seeds. Eighty-three percent of seeds of this type germinate. The gardener plants 90 seeds. Approximate the probability that fewer than 85 seeds germinate.
9. A bottler of drinking water fills plastic bottles with a mean volume of 998 milliliters (mL) and standard deviation The fill volumes are normally distributed. What proportion of bottles have volumes between and
10. The following figure is a probability density curve that represents the lifetime, in months, of a certain type of laptop battery.
11. A certain car model has a mean gas mileage of 34 miles per gallon (mpg) with a standard deviation A pizza delivery company buys 54 of these cars. What is the probability that the average mileage of the fleet is between 33.3 and
12. Find the area under the standard normal curve that lies between z = 0.5 and
13. According to a recent study, the weight of male babies less than two months old in the United States is normally distributed with mean 12.0 pounds and standard deviation 2.4 pounds. What proportion of babies weigh less than 9.1 pounds?
14. Using technology, use the Central Limit Theorem to find the indicated probability. The sample size is n, the population proportion is p, and the sample proportion is .
15. A gardener buys a package of seeds. Seventy-six percent of seeds of this type germinate. The gardener plants 120 seeds. Approximate the probability that the number of seeds that germinate is between 84.2 and 94.2 exclusive.
16. Use technology to solve the following problem: The mean annual income for people in a certain city (in thousands of dollars) is 44, with a standard deviation of 35. A pollster draws a sample of 59 people to interview. What is the probability that the sample mean income is between 42 and 48 (thousands of dollars)?
17. The following histograms each illustrate a sample. Which sample can be treated as approximately normal?
18. Use technology to solve the following problem: A normal population has a mean μ = 28 and standard deviation What proportion of the population is between 18 and 26?
19. For a particular diamond mine, 78% of the diamonds fail to qualify as "gemstone grade". A random sample of 106 diamonds is analyzed. Find the mean μ.
20. Using technology, use the normal approximation to find the indicated probability. The sample size is n, the population proportion of successes is p, and X is the number of successes in the sample.
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