Question

The following is the number of minutes to commute from home to work for a group of 25 automobile executives.

43	42	41	38	47	45	40	42	43	39	35	46	52
38	46	47	45	33	30	42	37	33	48	49	46

1. How many classes would you recommend?
2. What class interval would you suggest? (Round up your answer to the next whole number.)
3. Organize the data and plot a frequency distribution on a piece of paper. Comment on the shape of the frequency distribution. a.) It is not symmetric. b.)It is fairly symmetric, with most of the values between 40 and 49. c.)It is not very symmetric, but most of the values lie between 40 and 49.

Answer 1

(first part) How many classes would you recommend?

A rough approximation for number of classes k may be obtained from Sturges' rule

, k = 1 + 3.322 logN, where N is the number of measurements in the data

k=1+3.322*log(25)=5.64 ( next whole number is 6)

so number of classes=6

range=maximum-minimum=52-30=22

(second part)What class interval would you suggest?

class width/interval=range/k=22/6= 3.67( next whole number is 4)

(third part) Organize the data and plot a frequency distribution on a piece of paper. Comment on the shape of the frequency distribution. a.) It is not symmetric. b.)It is fairly symmetric, with most of the values between 40 and 49. c.)It is not very symmetric, but most of the values lie between 40 and 49.

right choice is c.)It is not very symmetric, but most of the values lie between 40 and 49.

first class will be 30 to 34 and so on

class interval	frequency(f)	cumulative frequency (cf)
30-34	3	3
34-38	2	5
38-42	5	10
42-46	7	17
46-50	7	24
52-54	1	25

the histogram showed it is not symmetric and most of the values lie between 40 and 49