The data represents the body mass index (BMI) values for 20 females. Construct a frequency distribution beginning with a lower class limit of 15.0 and use a class width of 6.0. What frequency is listed for the third class?

19.6, 25, 32.1, 34.5, 40.2, 49, 53.3,33.6, 30, 39.6, 54.6, 20.7, 41.1, 38.5, 15.9, 30.2, 49.8, 41.8, 31.7, 26.9