Question

If the class marks in a frequency distribution are 19.5, 26.5, 33.5, 40.5, then the class corresponding to the class mark 33.5 is :

• A. 16 - 23
• B. 23-30
• C. 30-37
• D. 37-41

Answer 1

Answer: (C)

30-37

Class mark is the mid point of the class interval.

Class size is the upper limit minus lower limit.

Given that class mark of a class is $6.5$ and

the class size is $26.5-19.5=33.5-26.5=40.5-33.5=7$

By option verification,

Opition A class mark is $\frac{16+23}{2}=\frac{39}{2}=19.5$ False

Option B class mark is $\frac{30+23}{2}=\frac{53}{2}=26.5$ False

Option C class mark is $\frac{30+37}{2}=\frac{67}{2}=33.5$ and

class size is $37-30=7$ True

Option D class mark is $\frac{37+41}{2}=\frac{78}{2}=39$ False

Therefore the class interval is $30-37$