Question

If class mark is $10$ and class width is $6$ then find the class.

Answer 1

In a class interval,

Class Mark $=\frac{U.L+L.L}{2}$

Class width $=U.L-L.L$

Where, $U.L=$ Upper limit, $L.L=$ Lower limit

It is given that,

Class Mark $=10$

$\Rightarrow$ $\frac{U.L+L.L}{2}=10$

$\Rightarrow$ $U.L+L.L=20$ --(1)

Class width $=6$

$\Rightarrow$ $U.L-L.L=6$ ---(2)

Lets add (1) and (2),

$U.L+L.L+U.L-L.L=20+6$

$\Rightarrow 2U.L=26$

$\Rightarrow U.L=\frac{26}{2}$

$\Rightarrow U.L=13$ --(3)

Lets substitute, $U.L=13$ in $U.L+L.L=20$

$\Rightarrow 13+L.L=20$

$\Rightarrow L.L=20-13$

$\Rightarrow L.L=7$ --(4)

Therefore, the required Class is $7-13$.