The surface-wave magnitude scale, Ms, measures the size of an earthquake. The Ms readings of earthquakes in the United States in 1985 are described by the histogram in Fig. 136.

a. Describe the shape of the distribution.
b. Identify the class that contains the 50th percentile, which is a measure of the center. What does it mean in this situation?
c. Estimate the number of U.S. earthquakes with Ms readings that were at least 3 AND less than 5. Round to the hundreds place.
d. Estimate the number of U.S. earthquakes that had Ms readings greater than or equal to 4. Round to the hundreds place.
e. California is known for having lots of earthquakes. In fact, there were 862 earthquakes in California in 1985. Estimate the percentage of U.S. earthquakes that happened in California in 1985.

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Magnitudes of Earthquakes 1200 1000 600 400 200 Surface-wave magnitude