In a stem-and-leaf plot, each number on the right side of the vertical lines is a piece of data.  For instance, the "4 | 7" means one student missed 47 days(!) of school.  Each number on the left of the line represents the ten's digit, and each number on the right of the line represents the one's digit.

We can find the total number of classmates by counting the numbers on the right side of the vertical lines, which in this case is 13.

The median of a group of data represents the physical middle of the data. 

If there is an even number of pieces of data, you take the middle two pieces of data, add them up, and divide by two for the median.

If there is an odd number of pieces of data (such as here), one number represents the median.  Since we have 13 pieces of data, the 7th value is the median, because we would have 6 pieces smaller or equal to it, and 6 pieces greater than or equal to it.

The seventh piece of data here is the 8, which is "0 | 8".  Since the ten's digit is 0, that means that the median number of days missed is 8.

Place the numbers in order from least to greatest:

36, 75, 81, 89, 89, 94, 111

Identify the middle number in the set. The answer is \(\displaystyle 89.\)

First, order the numbers from least to greatest:

\(\displaystyle 3011,3012,3021,3102,3112,3120,3201,3210,3211\)

Then, identify the middle number: \(\displaystyle 3112.\)

Answer: The median is 3112.

First, order the numbers from least to greatest:

\(\displaystyle 214, 241, 244, 412, 422, 422, 424\)

Identify the mode (most frequently appearing number): \(\displaystyle 422.\)

Identify the median (middle number): \(\displaystyle 412.\)

Finally, subtract the median from the mode: \(\displaystyle 422-412=10.\)

The answer is 10.

First, order the numbers from least to greatest.

\(\displaystyle 1034, 1073, 1081, 1144, 1187, 1187, 1198\)

Identify the middle number in the set.

Answer: The median is 1144.

First, order the numbers from least to greatest:

\(\displaystyle 2512, 2515, 2521, 2525, 2525, 2551, 2552\)

Identify the middle number: 2525

Answer: The median is 2525.

First, order the numbers from least to greatest:

\(\displaystyle 9198, 9818, 9881, 9889, 9889, 9891, 9918, 9981, 9989\)

Identify the middle number: \(\displaystyle 9889\)

Answer: The median is 9889.

First order the numbers from least to greatest:

\(\displaystyle 3334, 3343, 3343, 3434, 4334, 4343, 4434\)

Then, identify the middle number: 3434.

Answer: The median is 3434.

First, order the numbers from least to greatest:

\(\displaystyle 6333, 6336,6363,6363, 6366, 6633, 6663\)

Then, identify the middle number: \(\displaystyle 6363\)

Answer: the median is \(\displaystyle 6363\)

First, order the numbers from least to greatest:

\(\displaystyle 9008, 9008, 9009, 9080, 9090, 9099, 9800\)

Then, identify the middle number: \(\displaystyle 9080\).

Answer: The median in 9080.