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 four decimal places.)

x1 =	%
s1 =	%
x2 =	%
s2 =	%

(b) Let ₁ be the population mean for x₁ and let ₂ be the population mean for x₂. Find an 80% confidence interval for _{1 2}. (Round your answers to two decimal places.)

lower limit		%
upper limit		%