Question

Choose the correct answer in the following question:
The mid-value of a class interval is $42$ and the class size is $10$. The lower and upper limits are
(a) $37-47$
(b) $37.5-47.5$
(c) $36.5-47.5$
(d) $36.5-46.5$

Answer 1

Correct option is (a) $37-47$

Let upper limit and lower limit be $x$ and $y$ respectively.

$\Rightarrow \frac{x+y}{2}=42$ [ Given ]

$\therefore x+y=84$ ------ ( 1 )

Now, according to the question,

$\Rightarrow x-y=10$ ------ ( 2 )

Adding equation ( 1 ) and ( 2 ) we get,

$2x=94$

$\therefore x=47$

And $47-y=10$

$\therefore y=37$

$\therefore$ Required class interval $=37-47$