The magnitudes of the major earthquakes in 1999 are listed below.
$\begin{array} { l l l }
\text { 1/19/99 } & \text { New Ireland, Papua New Guinea } & 7 \
2 / 6 / 99 & \text { Santa Cruz Islands, S.Pacific Sea } & 7.3 \
3 / 4 / 99 & \text { Celebes Sea, Indonesia } & 7.1 \
4 / 5 / 99 & \text { New Britain, Papua New Guinea } & 7.4 \
4 / 8 / 99 & \text { E.Russia/N.E.China border } & 7.1 \
5 / 10 / 99 & \text { New Britain, Papua New Guinea } & 7.1 \
5 / 16 / 99 & \text { New Britain, Papua New Guinea } & 7.1 \
8 / 17 / 99 & \text { Izmit region, western Turkey } & 7.4 \
9 / 21 / 99 & \text { Taiwan } & 7.8 \
9 / 30 / 99 & \text { Oaxaca, Mexico } & 7.4 \
11 / 12 / 99 & \text { Bolu Province, northwest Turkey } & 7.2
\end{array}$
Find the mean, median, and mode of the magnitudes. Round to the nearest tenth.
A) mean 7.2; mode 7; median 7.3
B) mean 7.3; mode 7.2; median 7.2
C) mean 7.4; mode 7.2; median 7.2
D) mean 7.3; mode 7.1; median 7.2
E) mean 7.2; mode 7.1; median 7.2

Question

The magnitudes of the major earthquakes in 1999 are listed below.
$\begin{array} { l l l } 
\text { 1/19/99 } & \text { New Ireland, Papua New Guinea } & 7 \
2 / 6 / 99 & \text { Santa Cruz Islands, S.Pacific Sea } & 7.3 \
3 / 4 / 99 & \text { Celebes Sea, Indonesia } & 7.1 \
4 / 5 / 99 & \text { New Britain, Papua New Guinea } & 7.4 \
4 / 8 / 99 & \text { E.Russia/N.E.China border } & 7.1 \
5 / 10 / 99 & \text { New Britain, Papua New Guinea } & 7.1 \
5 / 16 / 99 & \text { New Britain, Papua New Guinea } & 7.1 \
8 / 17 / 99 & \text { Izmit region, western Turkey } & 7.4 \
9 / 21 / 99 & \text { Taiwan } & 7.8 \
9 / 30 / 99 & \text { Oaxaca, Mexico } & 7.4 \
11 / 12 / 99 & \text { Bolu Province, northwest Turkey } & 7.2
\end{array}$
Find the mean, median, and mode of the magnitudes. Round to the nearest tenth.
A) mean 7.2; mode 7; median 7.3
B) mean 7.3; mode 7.2; median 7.2
C) mean 7.4; mode 7.2; median 7.2
D) mean 7.3; mode 7.1; median 7.2
E) mean 7.2; mode 7.1; median 7.2

Quizplus · Accepted Answer

To find the mean, we add up all the magnitudes and divide by the total number of earthquakes:
$$\frac{7+7.3+7.1+7.4+7.1+7.1+7.1+7.4+7.8+7.4+7.2}{11} \approx 7.3$$
Therefore, the mean magnitude is 7.3.

To find the median, we need to put the magnitudes in order from least to greatest:
$$7, 7.1, 7.1, 7.1, 7.2, 7.3, 7.4, 7.4, 7.8$$
The median is the middle number, which in this case is 7.2 (since there are an odd number of magnitudes).

To find the mode, we look for the magnitude that appears most frequently. In this case, both 7.1 and 7.4 appear twice, so there is no single mode. Therefore, we say that the data set is bimodal with modes 7.1 and 7.4.

Thus, the best choice is D with the calculated mean, median 7.2 and the modes 7.1 and 7.4.

The Magnitudes of the Major Earthquakes in 1999 Are Listed