Question

Suppose a consumer organization was interested in studying weekly food & living expenses of college students living on college campuses in New York State. A survey of 40 students yielded the following (ordered array) to the nearest 10 cents.

38.3	50.0	54.5	60.0
39.4	50.5	55.6	61.2
40.0	51.2	56.3	62.3
41.2	51.7	57.0	63.8
43.7	51.8	57.0	64.0
45.0	52.0	57.4	64.5
47.5	53.8	58.5	65.0
48.2	53.8	58.5	65.0
48.5	54.0	59.4	66.2
50.0	54.0	60.0	67.0

I want to know how to find the bins, variables and the midpoints  

Answer 1

Suppose a consumer organization was interested in studying weekly food & living expenses of college students living on college campuses in New York State. A survey of 40 students yielded the following (ordered array) to the nearest 10 cents.

Minimum observation is 38.3 and maximum is 67

The range is 28.7

By considering a range of 30, and number of bins is 6, the suggested interval width is 30/6=5.

Class intervals are ( for convenience we strat with 38.1)

38.1-43.0

43.1-48.0

48.1-53.0

53.1-58.0

58.1-63.0

63.1-68.0

Therefore the bins used in excel to find frequency and histogram are 43,48,53,58,63,68.

Mid point for first interval is (38.1+43.0)/2 = 40.55

Similarly other midpoints are 45.55,50.55,55.55,60.55,65.55

class interval	mid point
38.1-43.0	40.55
43.1-48.0	45.55
48.1-53.0	50.55
53.1-58.0	55.55
58.1-63.0	60.55
63.1-68.0	65.55