A cup of coffee contains 130 mg of caffeine. If caffeine is eliminated from the body at a rate of 11 percent per hour, how much caffeine will remain in the body after 3 hours? Write the exponential function and solve.

An 11% hourly elimination rate means 89% remains each hour, so the hourly multiplier is 0.89. The exponential function is y = 130(0.89)^t, where t is the time in hours. After 3 hours, y = 130(0.89)^3 ≈ 91.7 mg, or about 92 mg; this matches choice B.

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