c. 30 times The Richter scale is a logarithmic scale for the energy release during an earth quake. For every increase by 1 in magnitude, the energy released is about 31.6 times larger. So calculate the magnitude difference by subtracting. 6.5 - 5.5 = 1.0 And then multiply by 31.6, giving 31.6. And since we're just looking for approximate values, select the answer that's closest which is option "c. 30 times"