Question

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.

(a) Use a calculator with mean and standard deviation keys to calculate x1, s1, x2, and s2. (Round your answers to two decimal places.)

x1 = 51.66 Correct: Your answer is correct. %

s1 = 7.93 Correct: Your answer is correct. %

x2 = 33.6 Correct: Your answer is correct. %

s2 = 12.25 Correct: Your answer is correct. %

(b) Let μ1 be the population mean for x1 and let μ2 be the population mean for x2. Find a 95% confidence interval for μ1 − μ2. (Round your answers to two decimal places.)

lower limit

upper limit

Answer 1

ANSWER:

x1=51.66

s1=7.93

x2=33.60

s2=12.26

b)

lower limit =12.77

upper limit =23.36