A random sample of 200 students was chosen from UMUC STAT 200 classes. The frequ

Question

A random sample of 200 students was chosen from UMUC STAT 200 classes. The frequency distribution below shows the distribution for study time each week (in hours). (Show all work. Just the answer, without supporting work, will receive no credit.)

(a) Complete the frequency table with frequency and relative frequency. Express the relative frequency to two decimal places.

(b) What percentage of the study times was at least 15 hours?

(c) In what class interval must the median lie? 5.0 – 9.9, 10.0 -14.9, 15.0 – 19.9, or 20.0 – 24.9?

Why?

Explanation / Answer

(a)

Study time            Frequency                      Relative frequency

0.0 - 4.9                6                                        0.03

5.0 - 9.9               24                                        0.12

10.0 - 14.9             50                                      0.25

15.0 - 19.9              70                                      0.35

20.0 - 24.9              50                                      0.25

---------------------------------------------------------------------------------

Total                    200                                     1.00

EXPLANATION: Relative frequency of each class is obtained by diving the frequency of the class by total frequency = 200.

Frequency of class 15.0 - 19.9 is obtained by multiplying the reltive frequency = 0.35 by 200.

Frequency of the missing class is got by subtracting from 200 the sum of other frequencies.

(b) At least 15 hours corresponds to 10 hours.

In terms of percentage: (10/200)X 100 = 5%

(c) Median will lie in Total frequency from below of 200/2 = 100 occurs., i.e., 6 + 24 + 50 +70 ,

i.e., class : 15.0 - 19.9

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