單項(xiàng)選擇題

The number of phone calls arriving at a switchboard each hour has been recorded and the following frequency distribution has been developed.
What is the cumulative frequency of the third class？（）

A.80
B.0.40
C.155
D.75


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1.單項(xiàng)選擇題A cumulative frequency distribution would provide（）.

A.a graph of a frequency distribution
B.a running total of the frequencies in the classes
C.the proportion of the total frequencies which fall into each class
D.a very cloudy picture of the frequencies

3.單項(xiàng)選擇題One rule that must always be followed in constructing frequency distributions is that （）.

A.the number of classes must be less than 10
B.each data point can only fall into one class
C.the width of each class is equal to the range
D.the number of intervals must be an odd number

4.單項(xiàng)選擇題One advantage of a stem and leaf plot over a frequency distribution is that （）.

A.it contains more class intervals
B.the values of the original data are retained
C.the class midpoints are used as the stem
D.the class midpoints are used as the leaf

5.單項(xiàng)選擇題The number of class intervals in a frequency distribution is usually between （）.

A.3 and 5
B.7 and 9
C.5 and 15
D.1 and 25