Mathematical Statistics with Applications
7th Edition
ISBN: 9781111798789
Author: Dennis O. Wackerly
Publisher: Cengage Learning
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Textbook Question
Chapter 7.2, Problem 26E
Refer to Exercise 7.11. Suppose that in the forest fertilization problem the population standard deviation of basal areas is not known and must be estimated from the sample. If a random sample of n = 9 basal areas is to be measured, find two statistics g1 and g2 such that
7.11 A forester studying the effects of fertilization on certain pine forests in the Southeast is interested in estimating the average basal area of pine trees. In studying basal areas of similar trees for many years, he has discovered that these measurements (in square inches) are normally distributed with standard deviation approximately 4 square inches. If the forester samples n = 9 trees, find the probability that the sample mean will be within 2 square inches of the population mean.
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An engineer is comparing voltages for two types of batteries (K and Q) using a sample of 7070 type K batteries and a sample of 8585 type Q batteries. The type K batteries have a mean voltage of 8.848.84, and the population standard deviation is known to be 0.3030.303. The type Q batteries have a mean voltage of 9.059.05, and the population standard deviation is known to be 0.3670.367. Conduct a hypothesis test for the conjecture that the mean voltage for these two types of batteries is different. Let μ1μ1 be the true mean voltage for type K batteries and μ2μ2 be the true mean voltage for type Q batteries. Use a 0.010.01 level of significance.
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Chapter 7 Solutions
Mathematical Statistics with Applications
Ch. 7.2 - Refer to Example 7.2. The amount of fill dispensed...Ch. 7.2 - Refer to Exercise 7.9. Assume now that the amount...Ch. 7.2 - A forester studying the effects of fertilization...Ch. 7.2 - Suppose the forester in Exercise 7.11 would like...Ch. 7.2 - The Environmental Protection Agency is concerned...Ch. 7.2 - If in Exercise 7.13 we want the sample mean to...Ch. 7.2 - Suppose that X1, X2,Xm and Y1, Y2,Yn are...Ch. 7.2 - Referring to Exercise 7.13, suppose that the...Ch. 7.2 - Applet Exercise Refer to Example 7.4. Use the...Ch. 7.2 - Applet Exercise Refer to Example 7.5. If 2 = 1 and...
Ch. 7.2 - Ammeters produced by a manufacturer are marketed...Ch. 7.2 - a If U has a 2 distribution with v df, find E(U)...Ch. 7.2 - Refer to Exercise 7.13. Suppose that n = 20...Ch. 7.2 - Prob. 22ECh. 7.2 - Applet Exercise a Use the applet Chi-Square...Ch. 7.2 - Applet Exercise Refer to Example 7.6. Suppose that...Ch. 7.2 - Applet Exercise Suppose that T is a t-distributed...Ch. 7.2 - Refer to Exercise 7.11. Suppose that in the forest...Ch. 7.2 - Applet Exercise Refer to Example 7.7. If we take...Ch. 7.2 - Applet Exercise Suppose that Y has an F...Ch. 7.2 - If Y is a random variable that has an F...Ch. 7.2 - Suppose that Z has a standard normal distribution...Ch. 7.2 - a Use Table 7, Appendix 3, to find F.01 for...Ch. 7.2 - Applet Exercise a Find t.05 for a t-distributed...Ch. 7.2 - Prob. 33ECh. 7.2 - Suppose that W1 and W2 are independent...Ch. 7.2 - Prob. 35ECh. 7.2 - Let S12 denote the sample variance for a random...Ch. 7.2 - Let Y1, Y2,,Y5 be a random sample of size 5 from a...Ch. 7.2 - Suppose that Y1, Y2,,Y5, Y6, Y,W, and U are as...Ch. 7.2 - Prob. 39ECh. 7.3 - The fracture strength of tempered glass averages...Ch. 7.3 - An anthropologist wishes to estimate the average...Ch. 7.3 - Suppose that the anthropologist of Exercise 7.43...Ch. 7.3 - Workers employed in a large service industry have...Ch. 7.3 - The acidity of soils is measured by a quantity...Ch. 7.3 - Prob. 47ECh. 7.3 - Prob. 48ECh. 7.3 - The length of time required for the periodic...Ch. 7.3 - Shear strength measurements for spot welds have...Ch. 7.3 - Refer to Exercise 7.50. If the standard deviation...Ch. 7.3 - Resistors to be used in a circuit have average...Ch. 7.3 - One-hour carbon monoxide concentrations in air...Ch. 7.3 - Unaltered bitumens, as commonly found in leadzinc...Ch. 7.3 - The downtime per day for a computing facility has...Ch. 7.3 - Prob. 56ECh. 7.3 - Twenty-five heat lamps are connected in a...Ch. 7.3 - Prob. 58ECh. 7.3 - Prob. 59ECh. 7.3 - Prob. 60ECh. 7.3 - Refer to Exercise 7.60. Suppose that n1 = n2 = n,...Ch. 7.3 - Prob. 62ECh. 7.3 - Refer to Exercise 7.62. Find the number of...Ch. 7.5 - Applet Exercise Suppose that Y has a binomial...Ch. 7.5 - Prob. 66ECh. 7.5 - Prob. 67ECh. 7.5 - Prob. 70ECh. 7.5 - Prob. 71ECh. 7.5 - A machine is shut down for repairs if a random...Ch. 7.5 - An airline finds that 5% of the persons who make...Ch. 7.5 - According to a survey conducted by the American...Ch. 7.5 - A pollster believes that 20% of the voters in a...Ch. 7.5 - a Show that the variance of Y/n, where Y has a...Ch. 7.5 - The manager of a supermarket wants to obtain...Ch. 7.5 - If the supermarket manager (Exercise 7.77) samples...Ch. 7.5 - Suppose that a random sample of 25 items is...Ch. 7.5 - Prob. 80ECh. 7.5 - Prob. 81ECh. 7.5 - Prob. 82ECh. 7.5 - Prob. 84ECh. 7.5 - Prob. 85ECh. 7.5 - Prob. 86ECh. 7.5 - Prob. 87ECh. 7 - The efficiency (in lumens per watt) of light bulbs...Ch. 7 - Refer to Exercise 7.88. What should be the mean...Ch. 7 - Prob. 90SECh. 7 - A retail dealer sells three brands of automobiles....Ch. 7 - From each of two normal populations with identical...Ch. 7 - Prob. 93SECh. 7 - Prob. 94SECh. 7 - The coefficient of variation (CV) for a sample of...Ch. 7 - Prob. 96SECh. 7 - Prob. 97SECh. 7 - Prob. 100SECh. 7 - Prob. 101SECh. 7 - Prob. 102SECh. 7 - Prob. 103SECh. 7 - Prob. 104SECh. 7 - If the probability that a person will suffer an...
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