The U.S. Geological Survey compiled historical data about Old Faithful Geyser (Yellowstone National Park) from 1870 to 1987. Letx₁be a random variable that represents the time interval (in minutes) between Old Faithful eruptions for the years 1948 to 1952. Based on9320observations, the sample mean interval wasx₁=64.8minutes. Letx₂be a random variable that represents the time interval in minutes between Old Faithful eruptions for the years 1983 to 1987. Based on23,585observations, the sample mean time interval wasx₂=71.2minutes. Historical data suggest that₁=9.05minutes and₂=12.76minutes. Let₁be the population mean ofx₁and let₂be the population mean ofx₂.

(a) Compute a90%confidence interval for₁-₂. (Use 2 decimal places.)lower limitupper limit