the ages of a sample of 25 salespersons are as follows: 21 24 24 26 28 28 30 30 31 32 34 34 35 36 37 38 40 41 43 45 45 45 47 53 56 manually draw a frequency histogram with six classes using range interval from 20 to 56. if there are one or more observations that fall on the boundary between classes, then count them as members of the left class. how many observations fall into the 5th class?