In the diagram, the y-axis represents the number of earthquakes that

Official Explanation

Statement 1: February 17. Beware of choosing February 14 just because it has the largest number of earthquakes registering 3 or greater—it also has the largest number of total earthquakes, so we’ll need to compute some actual proportions. Rather than calculate the proportion for each of the six days, start by eliminating days based on how they compare with other, similar days.

Start by looking for a day that has a high number of earthquakes rated 3+ but a low number of total earthquakes. February 17 fits the bill.

February 15, 16, and 18 all have a lower number of 3+ earthquakes but an equal or higher number of total earthquakes, so the proportion of earthquakes rates 3+ on these three days must be less than the proportion on February 17. Eliminate February 15, 16, and 18.

February 19 has a lower overall total but also a lower number of earthquakes rated 3+. The decline in the total is not as much as the decline in earthquakes rated 3+, so this day must also have a lower proportion than does February 17. (However, if you feel that this one is too close to eliminate up front, go ahead and calculate the actual proportion.)

Only February 14 and February 17 remain to be calculated. Find the number of 3+ quakes and divide by the total number or quakes. Note that each tick mark on the y-axis is equivalent to 10 quakes. Also, you can estimate a little.

Use your calculator to find the values

(# 3 or greater quakes that day) / (total # of quakes that day)
February 14 = 30/179 = 16.7%
February 17 = 20/114 = 17.5%

The proportion is higher on February 17.

Statement 2: 22%. The question stem tells you that you can approximate. Use the calculator to sum the daily totals: 180 + 130 + 140 + 115 + 115 + 110 = 790. Finally, 180 ÷ 790 = 22.8%.

Answer: D & B