(a) The range is (largest value) - (smallest value) = 80 - 30 = 50.
(b) The value of the median is the value of the middle term, after the terms have been arranged in increasing order. When given a graph like this one, you can spot the median easily: It's the x-value of the vertical line inside the box: 64.
(c) Look at the x-values of the two box endpoints: 38 and 74. Subtract the larger from the smaller: 74 - 38. This gives us the IQR: 74 - 38 = 36.
