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Chapter 1: Q3E (page 12)

Consider the population consisting of all computers of acertain brand and model, and focus on whether a computerneeds service while under warranty.

a. Pose several probability questions based on selecting a sample of 100 such computers.

b. What inferential statistics question might be answeredby determining the number of such computers in a sample of size 100 that need warranty service?

Short Answer

Expert verified

a.What is the expected number among the 100 that need warranty service.

b.Does the sample provide compelling evidenceforconcluding that more than 10% of all such computersneed warranty service?

Step by step solution

01

Given information

The population consists of all computers of a certain brand and model.

02

State the probability questions

a.

1)What is the expected number among the 100 that need warranty service.

2) How likely is it that the number needing warrantyservice will exceed the expected number by more than 10?

3)How likely is it that more than half of the sampled computerswill need or have needed warranty service?

03

State the inferential statistics questions

b.

Suppose that 15 of the 100 sampled needed warrantyservice. How confident can we be that the proportion ofallsuch computers needing warranty service is between.08 and .22? Does the sample provide compelling evidenceforconcluding ;that more than 10% of all such computersneed warranty service?

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Most popular questions from this chapter

Consider the strength data for beams given in Example

1.2.

a. Construct a stem-and-leaf display of the data. What appears to be a representative strength value? Do the observations appear to be highly

concentrated about the representative value or rather spread out?

b. Does the display appear to be reasonably symmetric about a representative value, or would you describe its shape in some other way?

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Allowable mechanical properties for structural design of metallic aerospace vehicles requires an approved method for statistically analyzing empirical test data. The article 鈥淓stablishing Mechanical Property Allowables for Metals鈥� (J. of Testing and Evaluation, 1998: 293鈥�299) used the accompanying data on tensile ultimate strength (ksi) as a basis for addressing the difficulties in developing such a method.

122.2 124.2 124.3 125.6 126.3 126.5 126.5 127.2 127.3

127.5 127.9 128.6 128.8 129.0 129.2 129.4 129.6 130.2

130.4 130.8 131.3 131.4 131.4 131.5 131.6 131.6 131.8

131.8 132.3 132.4 132.4 132.5 132.5 132.5 132.5 132.6

132.7 132.9 133.0 133.1 133.1 133.1 133.1 133.2 133.2

133.2 133.3 133.3 133.5 133.5 133.5 133.8 133.9 134.0

134.0 134.0 134.0 134.1 134.2 134.3 134.4 134.4 134.6

134.7 134.7 134.7 134.8 134.8 134.8 134.9 134.9 135.2

135.2 135.2 135.3 135.3 135.4 135.5 135.5 135.6 135.6

135.7 135.8 135.8 135.8 135.8 135.8 135.9 135.9 135.9

135.9 136.0 136.0 136.1 136.2 136.2 136.3 136.4 136.4

136.6 136.8 136.9 136.9 137.0 137.1 137.2 137.6 137.6

137.8 137.8 137.8 137.9 137.9 138.2 138.2 138.3 138.3

138.4 138.4 138.4 138.5 138.5 138.6 138.7 138.7 139.0

139.1 139.5 139.6 139.8 139.8 140.0 140.0 140.7 140.7

140.9 140.9 141.2 141.4 141.5 141.6 142.9 143.4 143.5

143.6 143.8 143.8 143.9 144.1 144.5 144.5 147.7 147.7

a. Construct a stem-and-leaf display of the data by first deleting (truncating) the tenths digit and then repeating each stem value five times (once for leaves 1 and 2, a second time for leaves 3 and 4, etc.). Why is it relatively easy to identify a representative strength value?

b. Construct a histogram using equal-width classes with the first class having a lower limit of 122 and an upper limit of 124. Then comment on any interesting features of the histogram.

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Frequency: 1 3 1 1 1

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