Question

To construct a histogram, Ankita observed the range of observations. She decided to divide that range into a number of parts. Then she does following calculation:
Range/no. of parts.

What are the terms used to describe
a. number of parts
b. range/no. of parts

• A. number of bars, width of bars
• B. frequency, class interval
• C. intervals, class width
• D. class, band width

Answer 1

The correct option is C intervals, class width

To construct a histogram, one has to divide the range of observations into few number of parts. This 'number of parts' is called as intervals. To decide on the number of intervals, as a rule of thumb, the square root of total observations is taken and is rounded off to the nearest integer. e.g. if there are 48 observations, take the square root of 48, which is 6.92. Round the value up and use 7
The next step is to decide how big each interval would be. To obtain that number one has to divide the range of observations by the number of intervals.

In this example, for the range 0-200,
$\frac{200}{7}=28.57$
Round this number up and use 30. This figure is called as the class width or the interval width.