The U.S. 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 8860 observations, the sample mean interval was x1 = 61.4 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 24,170 observations, the sample mean time interval was x2 = 70.6 minutes. Historical data suggest that ?1 = 8.00 minutes and ?2 = 12.55 minutes. Let ?1 be the population mean of x1 and let ?2 be the population mean of x2. (a) Compute a 90% confidence interval for ?1 – ?2. (Use 2 decimal places.) lower limit = upper limit=
The U.S. 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 8860 observations, the sample mean interval was x1 = 61.4 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 24,170 observations, the sample mean time interval was x2 = 70.6 minutes. Historical data suggest that ?1 = 8.00 minutes and ?2 = 12.55 minutes. Let ?1 be the population mean of x1 and let ?2 be the population mean of x2.
(a) Compute a 90% confidence interval for ?1 – ?2. (Use 2 decimal places.)
lower limit =
upper limit=
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