If m is the mid-point and l is the upper class limit

Question:

If m is the mid-point and l is the upper class limit of a class in a continuous frequency distribution, then lower class limit of the class is

(a) 2 m+l                      

(b) 2 m-l                    

(c) m-l                           

(d) m-2l

Solution:

(b) Let x and y be the lower and upper class limit of a continuous frequency distribution.

Now, mid-point of a class = (x + y)/2 = m [given]

=> x + y = 2 m =x + l = 2m

[∴ y = l = upper class limit (given)]

=> x = 2 m-l

Hence, the lower class limit of the class is 2m – l.

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