Question

finding the median from a dot plot
the dot plots show rainfall totals for several spring storms in highland areas and lowland areas.
what is the median rainfall for the highland storms?
what is the median rainfall for the lowland storms?

Explanation:

Step1: Count data - points for highlands

Count the number of dots in the highlands dot - plot. There are 50 dots.

Step2: Calculate median position for highlands

Since \(n = 50\) (an even number), the median is the average of the \(\frac{n}{2}\)th and \((\frac{n}{2}+ 1)\)th ordered data - values. \(\frac{n}{2}=25\) and \(\frac{n}{2}+1 = 26\). Counting from the left on the highlands dot - plot, the 25th and 26th ordered values are both 16. The median for highlands is \(\frac{16 + 16}{2}=16\).

Step3: Count data - points for lowlands

Count the number of dots in the lowlands dot - plot. There are 30 dots.

Step4: Calculate median position for lowlands

Since \(n = 30\) (an even number), the median is the average of the \(\frac{n}{2}\)th and \((\frac{n}{2}+ 1)\)th ordered data - values. \(\frac{n}{2}=15\) and \(\frac{n}{2}+1 = 16\). Counting from the left on the lowlands dot - plot, the 15th value is 12 and the 16th value is 12. The median for lowlands is \(\frac{12+12}{2}=12\).

Answer:

Median for highland storms: 16
Median for lowland storms: 12