Question

Find the class mark of the class 800−899.
A. 859.5
B. 800
C. 849.5
D. 944.5

Answer 1

In order to find the class mark of the class 800−899, we will use the formula
Class mark of a class interval $=\dfrac{\text{Actual lower limit}+\text{Actual upper limit}}{2}$ . From the class interval 800−899, we will get the lower limit of the class =800 and upper limit =899. Substituting these in the formula, we will get the required solution.

Complete step-by-step answer:
We have to find the class mark of the class 800−899. We know that class mark is the mid-value of each class interval. We will be using the formula given below
Class mark of a class interval $=\dfrac{\text{Actual lower limit}+\text{Actual upper limit}}{2}$
This means that
Class mark of a class interval $=\dfrac{\text{Sum of class boundaries}}{2}$
We have the class 800−899. Let us see the upper limit and lower limit of the class.
Lower limit of the class =800
Upper limit of the class =899
Now, we can substitute these in the formula for the class mark of a class. We will get
Class mark of a class interval $=\dfrac{\text{800+899}}{2}$
When we add the terms of the numerator, we will get
Class mark of a class interval $=\dfrac{\text{1699}}{2}$
Let us now do the division operation. We will get
Class mark of a class interval $=849.5$

So, the correct answer is “Option C”.

Note: You may write the formula for class mark of a class interval as $=\dfrac{\text{Actual lower limit}-\text{Actual upper limit}}{2}$ . You may mistake class marks for class size. Class size is the range or size of the class which is given as $\text{Upper limit}-\text{Lower limit}$ .