Statistics for Engineers and Scientists
4th Edition
ISBN: 9780073401331
Author: William Navidi Prof.
Publisher: McGraw-Hill Education
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Chapter 1, Problem 3SE
The specification for the pull strength of a wire that connects an integrated circuit to its frame is 10 g or more. Units made with aluminum wire have a defect rate of 10%. A redesigned manufacturing process, involving the use of gold wire, is being investigated. The goal is to reduce the rate of defects to 5% or less. Out of the first 100 units manufactured with gold wire, only 4 are defective. True or false:
- a. Since only 4% of the 100 units were defective, we can conclude that the goal has been reached.
- b. Although the sample percentage is under 5%, this may represent sampling variation, so the goal may not yet be reached.
- c. There is no use in testing the new process, because no matter what the result is, it could just be due to sampling variation.
- d. If we sample a large enough number of units, and if the percentage of defective units is far enough below 5%, then it is reasonable to conclude that the goal has been reached.
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The specification for the pull strength of a wire that connects an integrated circuit to its frame is 10 g or more. Units made with aluminum wire have a defect rate of 10%. A redesigned manufacturing process, involving the use of gold wire, is being investigated. The goal is to reduce the rate of defects to 5% or less. Out of the first 100 units manufactured with gold wire, only 4 are defective. True or false: a) Since only 4% of the 100 units were defective, we can conclude that the goal has been reached. b) Although the sample percentage is under 5%, this may represent sampling variation, so the goal may not yet be reached. c) There is no use in testing the new process, because no matter what the result is, it could just be due to sampling variation. d) If we sample a large enough number of units, and if the percentage of defective units is far enough below 5%, then it is reasonable to conclude that the goal has been reached.
Suppose that samples of polythene bags from two manufacturers A and B are tested by a prospective buyer for bursting pressure, with the following results:
If the prices are the same, which manufacture’s bags would be preferred by the buyer? Why?
How heavy a load (pounds) is needed to pull apart pieces of Douglas fir 4 inches long and 1.5 inches square? Here are data from students doing a laboratory exercise:
33,190 31,860 32,590 26,520 33,280
32,320 33,020 32,030 30,460 32,700
23,040 30,930 32,720 33,650 32,340
24,050 30,170 31,300 28,730 31,920
Suppose that the strength of pieces of wood like these follows a Normal distribution with standard deviation 3000 pounds. Give a 90% confidence interval for the mean load required to pull the wood apart.
__ to __ lb
Chapter 1 Solutions
Statistics for Engineers and Scientists
Ch. 1.1 - Each of the following processes involves sampling...Ch. 1.1 - If you wanted to estimate the mean height of all...Ch. 1.1 - True or false: a. A simple random sample is...Ch. 1.1 - A sample of 100 college students is selected from...Ch. 1.1 - A certain process for manufacturing integrated...Ch. 1.1 - Refer to Exercise 5. True or false: a. If the...Ch. 1.1 - To determine whether a sample should be treated as...Ch. 1.1 - A medical researcher wants to determine whether...Ch. 1.1 - A medical researcher wants to determine whether...Ch. 1.2 - True or false: For any list of numbers, half of...
Ch. 1.2 - Is the sample mean always the most frequently...Ch. 1.2 - Is the sample mean always equal to one of the...Ch. 1.2 - Is the sample median always equal to one of the...Ch. 1.2 - Find a sample size for which the median will...Ch. 1.2 - For a list of positive numbers, is it possible for...Ch. 1.2 - Is it possible for the standard deviation of a...Ch. 1.2 - In a certain company, every worker received a...Ch. 1.2 - In another company, every worker received a 5%...Ch. 1.2 - A sample of 100 adult women was taken, and each...Ch. 1.2 - In a sample of 20 men, the mean height was 178 cm....Ch. 1.2 - Each of 16 students measured the circumference of...Ch. 1.2 - Refer to Exercise 12. a. If the measurements for...Ch. 1.2 - There are 10 employees in a particular division of...Ch. 1.2 - Quartiles divide a sample into four nearly equal...Ch. 1.2 - In each of the following data sets, tell whether...Ch. 1.3 - The weather in Los Angeles is dry most of the...Ch. 1.3 - Forty-five specimens of a certain type of powder...Ch. 1.3 - Refer to Table 1.2 (in Section 1.2). Construct a...Ch. 1.3 - Following are measurements of soil concentrations...Ch. 1.3 - A certain reaction was run several times using...Ch. 1.3 - Sketch a histogram for which a. The mean is...Ch. 1.3 - The figure below is a histogram showing the...Ch. 1.3 - The histogram below presents the compressive...Ch. 1.3 - Refer to Table 1.4 (in Section 1.3). a. Using the...Ch. 1.3 - Refer to Table 1.5 (in Section 1.3). a. Using the...Ch. 1.3 - The following table presents the number of...Ch. 1.3 - Which of the following statistics cannot be...Ch. 1.3 - A sample of 100 resistors has an average...Ch. 1.3 - Following are boxplots comparing the amount of...Ch. 1.3 - Following are summary statistics for two data...Ch. 1.3 - Match each histogram to the box plot that...Ch. 1.3 - Prob. 17ECh. 1.3 - Match each scatterplot to the statement that best...Ch. 1.3 - Prob. 19ECh. 1 - A vendor converts the weights on the packages she...Ch. 1 - Refer to Exercise 1. The vendor begins using...Ch. 1 - The specification for the pull strength of a wire...Ch. 1 - A coin is tossed twice and comes up heads both...Ch. 1 - The smallest number on a list is changed from 12.9...Ch. 1 - There are 15 numbers on a list, and the smallest...Ch. 1 - There are 15 numbers on a list, and the mean is...Ch. 1 - The article The Selection of Yeast Strains for the...Ch. 1 - Concerning the data represented in the following...Ch. 1 - True or false: In any boxplot, a. The length of...Ch. 1 - For each of the following histograms, determine...Ch. 1 - In the article Occurrence and Distribution of...Ch. 1 - The article Vehicle-Arrival Characteristics at...Ch. 1 - The cumulative frequency and the cumulative...Ch. 1 - The article Hydrogeochemical Characteristics of...Ch. 1 - Water scarcity has traditionally been a major...Ch. 1 - Prob. 18SECh. 1 - The article The Ball-on-Three-Ball Test for...
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