Question

Find the class mark of the class $11 - 19$.
A.15
B.11
C.19
D.$14.5$

Answer 1

First we will use the formula to calculate the class mark is $\dfrac{{{\text{Lower Limit}} + {\text{Upper Limit}}}}{2}$. Then we will substitute 11 for lower limit and 19 for upper limit in the given formula to find the value of class mark.

Complete step-by-step answer:
We are given that the class interval is $11 - 19$.
We know that the formula to calculate the class mark is $\dfrac{{{\text{Lower Limit}} + {\text{Upper Limit}}}}{2}$.
Finding the value of lower limit and upper limit from the given class interval, we get
${\text{Lower Limit}} = 11$
${\text{Upper Limit}} = 19$
Substituting the value of lower limit and upper limit in the above class mark, we get

$$\Rightarrow {\text{Class Mark}} = \dfrac{{11 + 19}}{2} \\\ \Rightarrow {\text{Class Mark}} = \dfrac{{30}}{2} \\\ \Rightarrow {\text{Class Mark}} = 15 \\\$$

Therefore, the value of the class mark is 15.

Hence, option A is correct.

Note: We know that a statistics value within a class interval, especially its midpoint or the nearest integral value, used to represent the interval for computational convenience. The class mark is the sum of class boundaries by 2. Write the values from the question properly and avoid calculation mistakes.