The magnitude of earthquakes since 1900 that measures 0.1 or higher on the Richter scale in California is approximately normally distributed with μ=6.2 and σ=0.5, according to data obtained from the U.S. Geological Survey.
(a). Determine the 40th percentile of the magnitude of earthquakes in California.
(b). Determine the magnitude of earthquakes that make up the middle 85% of magnitudes.