Class limits
These are numerical values, which limits uq extended of a given class that is all the observations in a provided class are expected to fall in the interval which is bounded by the class limits for illustration 15 & 19 are class limits as in the table of the illustration above.
Class boundaries
These are statistical boundaries, which separate one class from the other. They are normally determined by adding the lower class limit to the next upper class limit and dividing by 2 for illustration in the above table the class boundary among 19 and 20 is 19.5 that is = (19 + 20)/2
Age (yrs)
No. of Students (f)
mid points (x)
x-a = d
D/c = u
fu
15 - 19
21
17
-15
-3
-63
20 - 24
35
22
-10
-2
-70
25 - 29
38
27
-5
-1
-38
30 - 34
49
32(A)
0
35 - 39
31
37
+5
+
40 - 44
19
42
+10
+2
193
-102