Question

The following data represents the amount of gasoline purchased in gallons for a sample of 25 cars that use a particular service station on the New Jersey Turnpike:

97.   108   115    123   132    91   102    102    116    129   130    104    115
98.   111    117   124   100 117    116   122     117   113    128    122  

1. Form a stem and leaf.

2. Construct the percentage and the cumulative percentage distribution (using 90 as the lower bound of the first class with a width equal to 10).

Classes	Frequency	%	Cumulative %	Midpoints	Bins

3. Plot the percentage histogram.

4. Describe the shape of these data set.

5. What amount of gasoline (in gallons) is most likely to be purchased? Justify your answer.

Answer 1

a)

Stem	Leaf
9	1
10	0 2 2 4 8
11	1 3 5 5 6 6 7 7 7
12	2 2 3 4 8 9
13	0 2

b)

Classes	Frequency %	Cumulative frequency %	Midpoints	Bin
90 to 99	4%	4%	94.5	90
100 to 109	22%	26%	104.5	100
110 to 119	39%	65%	114.5	110
120 to 129	26%	91%	124.5	120
130 to 139	9%	100%	134.5	130

c)

d)

It is a bell curve(normal distribution).

e)

The median comes out to be 116. This amount of gasoline is most likely to be purchased.