# Thread: I cant figure out the number of classes

1. ## I cant figure out the number of classes

from these numbers I have to make a six column f/d table
30 26 16 23 22 10 8 15 16 23
29 30 22 15 24 9 5 4 15 24
21 24 16 14 21 13 6 2 23 29
24 21 27 13 20 8 4 3 24 20
22 18 23 23 17 7 6 1 16 17

(a) construct a six column f/d table

i tried using 5 classes 6 classes 10, 15 it just doesnt work
I know how to figure out the rest of the problem because its making a histogram but i cant figure out the number of classes to use to move onto the histogram

2. I am not sure what you mean by "it doesn't work". All of those classes should and do work. If you can tell my why it doesn't work I can perhaps help you.

3. what I mean is I have to construct a histogram and isnt a histogram suppose to go up and come back down sort of like a hill
but if i use the numbers in those classes i have like several hills it goes up annd down then back up and back down
if that makes sense

4. Depending on the distribution shape a histogram can look very different from an up and down hill. It can go up and down a lot if that's how the numbers work out.

5. oh ok I just dont want to be wrong I was just following his example and of course his works out perfect but if it's allowed to go up and down several time maybe I should just take a shot at it
I used a class of 10 and it went up and down several times I just dont want the polygon to look really weird that its wrong

6. I just seen a couple that go up and down several times on google imagesso i hope mine is right

7. Dear, the least no. in dataset is 1 & max. is 30. The total no. of datapoints are 50.
The no. of classes can be (1) Sqrt of 50=7.07 say 8 OR (2) 1 +3.332 Log 50=6.66 say7. Hence the dataset of 50 points can be divided into 7 classes.
Now classwidth = ( Max. - Min. + 1 ) / 7 =( 30 -1 +1) /7 = 4.28 say 5.
Hence classes are 0-4, 5-9, 10-14, 15-19, 20-24, 25-29 & 30-34.

8. could a histogram go up and down several times and have sveral peaks because if so i have a range of 30, number of classes 10, and class interval of 3
1-3 3
4-6 5
7-9 4
10-12 1

so as you see the histogram will go from 3 to 5 then back to 4 and if i continue it will go back up then down and up. can a histogram go up and down with several peaks if so ill use those numbers i have

9. A histogram can have several peaks.

10. ok thank you I just hope its right for him because he never showed us to a histogram with several peaks

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