What is the mean for this list of numbers? 3, 8, 10, 19

An equation where variables are used to represent known values—function notation true or false

Can someone answer this question? : )

The given dot plot represents the average daily temperatures, in degrees fahrenheit, recorded in a town during the first 15 days of september. if the dot plot is converted to a box plot, the first quartile would be drawn at __ , and the third quartile would be drawn at link to the chart is here