Question

What is the class mark of the interval \[27-32\]?

Answer 1

Hint: In order to find the class mark of the given interval \[27-32\], we must find the average of the given class interval by considering the upper limit and the lower limit values to find out the average. The average value we obtain will be our required value.

Complete step-by-step solution:
Now let us learn about the class marks of an interval. Class mark is also called the mid-point of the interval. It is the centre bar of a histogram. Class mark is helpful in finding out the mean for the group frequency. Even if the class intervals are equal or unequal, we can find out the midpoint of the particular class interval. In statistics for a frequency distribution table, all classes are represented using their class marks.
Now let us find the class mark of the interval \[27-32\].
We have, upper limit\[=32\] and lower limit\[=27\]
Now let us find the average of the class interval by taking the upper and the lower limit values.
\[classmark=\dfrac{27+32}{2}=29.5\]
\[\therefore \] The class mark of the interval \[27-32\] is \[29.5\].

Note: If we have our frequencies with no boundaries, then we will be assuming a value from the frequencies as the mid value in statistics. With the help of class marks, we can easily find out the mean of the frequencies as it represents the entire interval. We can apply this class mark method in all of the three methods of finding mean. They are: direct mean method, the assumed mean method and the step deviation method.