Question 672546: Construct a grouped frequency distribution for the following 28 scores using a class width of 4:
15 32 23 31 29 26 21 15 34 25 26 33 27 17
26 12 24 19 27 30 22 30 30 24 25 35 18 24
Answer by jim_thompson5910(35256)   (Show Source):
You can put this solution on YOUR website! Start with the original data set
15,32,23,31,29,26,21,15,34,25,26,33,27,17,26,12,24,19,27,30,22,30,30,24,25,35,18,24
and sort from least to greatest to get
12,15,15,17,18,19,21,22,23,24,24,24,25,25,26,26,26,27,27,29,30,30,30,31,32,33,34,35
The min is 12. Each class has a width of 4. So the classes used are:
12-15, 16-19, 20-23, 24-27, 28-31, 32-35
Notice how there are 4 values in each class (eg: 12-15 has 4 values and they are 12, 13, 14, 15). Also, notice how the classes do not overlap.
Now assign each data value in the original list to the appropriate class. For example, the value 19 belongs in the class 16-19 while the value 25 belongs in the class 24-27. Do this for EVERY value in the list to get the following
| Class |
Data |
| 12-15 |
15,15,12 |
| 16-19 |
17,19,18 |
| 20-23 |
23,21,22 |
| 24-27 |
26,25,26,27,26,24,27,24,25,24 |
| 28-31 |
31,29,30,30,30 |
| 32-35 |
32,34,33,35 |
Hopefully this table is straightforward to read. If not, then row 4 (class 24-27) for instance says that the values 26,25,26,27,26,24,27,24,25,24 all lie in the range from 24 to 27. So they belong in the class 24-27.
Now count up the frequencies in each class. Eg: There are 3 values in the first class, so the frequency for 12-15 is 3. This gives you the updated table:
| Class |
Data |
Frequency |
| 12-15 |
15,15,12 |
3 |
| 16-19 |
17,19,18 |
3 |
| 20-23 |
23,21,22 |
3 |
| 24-27 |
26,25,26,27,26,24,27,24,25,24 |
10 |
| 28-31 |
31,29,30,30,30 |
5 |
| 32-35 |
32,34,33,35 |
4 |
The last step is to delete the middle data column to get this final answer
| Class |
Frequency |
| 12-15 |
3 |
| 16-19 |
3 |
| 20-23 |
3 |
| 24-27 |
10 |
| 28-31 |
5 |
| 32-35 |
4 |
I hope this makes sense. If not, please let me know. Thanks.
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