Question

Find the class mark and class size of the class interval 15-20.

Answer 1

Answer:

Step-by-step explanation:

There are certain rules to be remembered while constructing a grouped frequency distribution in this question.

1. The number of classes should be between 5 and 20.

2. If possible, the magnitude of the class must be 5 or multiple of 5.

3. Lower limit of the first class must be multiple of 5.

So, class interval would be like this:-

Class Interval

5 - 15                                     

15 - 25

25 - 35

35 - 45

45 - 55

And so on.....

As we know that a is the class mark and h is its class size, then lower limit and upper limit will be -

a - h/2 and a + h/2.

So, first class interval will be 5 - 15 and the fifth class interval will be

 45 - 55.

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Answer 2

Answer:

Thus, the class mark is $17.5$ and class size is $5$ of the class interval $15-20$.

Step-by-step explanation:

Concept:

The distance between the upper and lower limits of the class interval is known as the class size. Given by b-a, where a denotes the lower limit and b the upper limit. The specific position in the middle of the class interval is referred to as the class mark or the class midpoint.

Given:

Class interval $= 15-20$

To find:

We have to find the class mark and class size of the provided class interval.

Solution:

The provided class interval $= 15-20$

Here,

Upper limit $=20$, and Lower limit$=15$

Then, Class size,

$= 20-15\\=5$

Class-mark $=$ Upper limit $+$ Lower limit$/2$

$=\frac{15+20}{2}$

$=17.5$

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