(a) Use a calculator with mean and standard deviation keys to calculate x1, s1, x2, and s2. (Round your answers to four decimal places.) x1 = % s1 = % x2 = % s2 = % (b) Let μ1 be the population mean for x1 and let μ2 be the population mean for x2. Find a 99% confidence interval for μ1 − μ2. (Round your answers to two decimal places.) lower limit % upper limit %
Contingency Table
A contingency table can be defined as the visual representation of the relationship between two or more categorical variables that can be evaluated and registered. It is a categorical version of the scatterplot, which is used to investigate the linear relationship between two variables. A contingency table is indeed a type of frequency distribution table that displays two variables at the same time.
Binomial Distribution
Binomial is an algebraic expression of the sum or the difference of two terms. Before knowing about binomial distribution, we must know about the binomial theorem.
For large U.S. companies, what percentage of their total income comes from foreign sales? A random sample of technology companies (IBM, Hewlett-Packard, Intel, and others) gave the following information.†
| Technology companies, % foreign revenue: x1; n1 = 16 | |||||||
| 62.8 | 55.7 | 47.0 | 59.6 | 55.3 | 41.0 | 65.1 | 51.1 |
| 53.4 | 50.8 | 48.5 | 44.6 | 49.4 | 61.2 | 39.3 | 41.8 |
Another independent random sample of basic consumer product companies (Goodyear, Sarah Lee, H.J. Heinz, Toys 'R' Us) gave the following information.
| Basic consumer product companies,% foreign revenue: x2; n2 = 17 | |||||||
| 28.0 | 30.5 | 34.2 | 50.3 | 11.1 | 28.8 | 40.0 | 44.9 |
| 40.7 | 60.1 | 23.1 | 21.3 | 42.8 | 18.0 | 36.9 | 28.0 |
| 32.5 |
Assume that the distributions of percentage foreign revenue are mound-shaped and symmetric for these two company types.
| x1 = | % |
| s1 = | % |
| x2 = | % |
| s2 = | % |
(b) Let μ1 be the population mean for x1 and let μ2 be the population mean for x2. Find a 99% confidence interval for μ1 − μ2. (Round your answers to two decimal places.)
| lower limit | % | |
| upper limit | % |
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