Question

In a frequency distribution, the mid-value of a class is 15 and the class intervals is 4. The lower limit of the class is

Options

• 10

• 12

• 13

• 14

Answer 1

Let l and m respectively be the lower and upper limits of the class. Then the mid-value of the class is `(l+m)/2`  and the class-size is(m-l) .

Therefore, we have two equations

`(l+m)/2 = 15`

⇒ l + m = 30

m - l = 4

Subtracting the second equation from the first equation, we have

`(l+m)-(m-l)=30-4`

`⇒l+m-m+l=26`

`⇒2l=26`

`⇒l=13`