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习题答案

Solutions:
1. Statistics can be referred to as numerical facts. In a broader sense, statistics is the field of study dealing with the collection, analysis, presentation and interpretation of data.

2.
a. The ten elements are the ten tablet computers
b. 5 variables: Cost ($), Operating System, Display Size (inches), Battery Life (hours), CPU Manufacturer
c. Categorical variables: Operating System and CPU Manufacturer  Quantitative variables: Cost ($), Display Size (inches), and Battery Life (hours)
d. Variable Measurement Scale Cost ($) Ratio Operating System Nominal Display Size (inches) Ratio Battery Life (hours) Ratio CPU Manufacturer Nominal

3.
a. Average cost = 5829/10 = $582.90
b. Average cost with a Windows operating system = 3616/5 = $723.20  Average cost with an Android operating system = 1714/4 = $428.5  The average cost with a Windows operating system is much higher.
c. 2 of 10 or 20% use a CPU manufactured by TI OMAP  d. 4 of 10 or 40% use an Android operating system  

4.
a. There are eight elements in this data set; each element corresponds to one of the eight models of cordless telephones  b. Categorical variables: Voice Quality and Handset on Base  Quantitative variables: Price, Overall Score, and Talk Time  c. Price – ratio measurement  Overall Score – interval measurement  Voice Quality – ordinal measurement  Handset on Base – nominal measurement  Talk Time – ratio measurement 5. a. Average Price = 545/8 = $68.13  b. Average Talk Time = 71/8 = 8.875 hours
c. Percentage rated Excellent: 2 of 8 2/8 = .25, or 25%  d. Percentage with Handset on Base: 4 of 8 4/8 = .50, or 50%