Question

Consider the classes: 4 - 9, 10 - 15, 16 - 21, 22 - 27. The width of each class is

• A. 4
• B. 5
• C. 6
• D. 4.5

Answer 1

The correct option is C 6

Class width is the difference of the upper limit and lower limit of a class interval.
The class intervals: 4 - 9, 10 - 15, 16 - 21, … are not continuous.
To make the class intervals continuous, we first determine the difference between upper limit of a class and lower limit of the next class.
$\Rightarrow$ Difference = 10 – 9 = 1
If half of this difference is added to the upper class limit and subtracted from the lower class limit, the class intervals will become continuous.
$\Rightarrow$ Half of the difference = $\frac{1}{2}$ = 0.5

Now, the class intervals will become
$\begin{array}{cc}\text{Class intervals}& \text{Continuous class interval}\\ 4-9& (4–0.5)–(9+0.5)=3.5-9.5\\ 10-15& (10–0.5)–(15+0.5)=9.5-15.5\\ 16-21& (16–0.5)–(21+0.5)=15.5-21.5\end{array}$
∴ Class width = 9.5 – 3.5
= 6
Hence, the correct answer is option (c).