STEM AND LEAF PLOT:
2 | 1 1 2
3 | 1 3
4 | 4 5
corresponds to the dataset: 21, 21, 22, 31, 33, 44, 45. This dataset is represented by the given stem and leaf plot. This plot helps to put the data in order. 2, 3 and 4 are the stems (in this case, they represent 20, 30, 40) and the other numbers are the leaves; so for the stem 2 the leaves are 1, 1, 2, representing the numbers 20+1, 20+1, 20+2, that is, 21, 21, 22; for stem 3 we have 30+1, 30+3, that is, 31, 33; for stem 4 we have 40+4, 40+5, that is, 44, 45. The median requires the dataset to be ordered (lowest to highest).
Mean=(21+21+22+31+33+44+45)/7=217/7=31.
Mode=21 (because 21 is the only repeated number).
Range=highest-lowest=45-21=24.
Median is central value of the dataset=31.