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1. [0/0.3 Points] DETAILS PREVIOUS ANSWERS BBUNDERSTAT12 7.2.001.MI.SA. MY NOTES ASK YOUR TEACHER PRACTICE ANOTHER This question has several parts that must be completed sequentially. If you skip a part of the question, you will not receive any points for the skipped part, and you will not be able to come back to the skipped part. Tutorial Exercise Use the Student's t distribution to find to for a 0.95 confidence level when the sample is 26. Step 1 Recall that a Student's t distribution table lists critical values , for a c confidence level. The table is arranged by column headings for c and by row headings for degrees of freedom d.f. Decide which column to use by identifying the confidence level value. C = 0.05 x 0.95 Step 2 We are given that the sample size is 26. Therefore, n = Decide which row of the table to use by calculating the degrees of freedom using the formula d.f. = n - 1. d.f. = n - 17. [0.0910527 Points] DETAILS PREVIOUS ANSWERS BBUNDERSTAT12 7.4.019. MY NOTES ASK YOUR TEACHER PRACTICE ANOTHER The US. Geological Survey compiled historical data about Old Faithful Geyser (Yellowstone National Park) from 1870 to 1987. Let X1 be a random variable that represents the time interval (in minutes) between Old Faithful eruptions for the years 1948 to 1952. Based on 9760 observations, the sample mean interval was x1 = 63.4 minutes. Let x2 be a random variable that represents the time interval in minutes between Old Faithful eruptions for the years 1983 to 1987. Based on 24,053 observations, the sample mean time interval was )72 = 71.2 minutes. Historical data suggest that 0'1 = 9.33 minutes and 0'2 = 11.57 minutes. Let [.11 be the population mean of x1 and let #2 be the population mean of x2. (a) Compute a 95% condence interval for [.11 - [.12. (Use 2 decimal places.) lower limit 754 Ix upper limit 3.0:. Ix 3. [0.24/0.27 Points] DETAILS PREVIOUS ANSWERS BBUNDERSTAT12 7.4.013. MY NOTES ASK YOUR TEACHER PRACTICE ANOTHER 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.t Technology companies, % foreign revenue: x1; 01 = 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 1.8 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, $1, X2, and S2. (Round your answers to two decimal places.) X 1 = 51.66 S1 = 7.93 % X? = 33.6 S? = 12.26 % (b) Let M1 be the population mean for x1 and let /2 be the population mean for X2. Find a 99% confidence interval for M1 - M2. (Round your answers to two decimal places.) lower limit 8.2 % upper limit 27.99