Question:
In a frequency distribution, the mid value of a class is 10 and the width of the class is 6. The lower limit of the class is
(a) 6
(b) 7
(c) 8
(d) 12
Solution:
(b) Let x and y be the upper and lower class limit in a frequency distribution.
Now, mid value of a class (x + y )/2=10 [given]
=> x + y = 20 …(i)
Also, given that, width of class x- y = 6 …(ii)
On adding Eqs. (i) and (ii), we get
2x =20+ 6
=> 2x =26 => x = 13
On putting x = 13 in Eq. (i), we get
13+y = 20=> y = 7
Hence, the lower limit of the class is 7.