Question

Below given is the pulse count of 40 patients.
66, 79, 89, 67, 72, 82, 85, 80, 82, 81, 67, 87, 71, 68, 63, 74, 73, 86, 84, 75, 85, 80, 85, 61, 75, 85, 80, 85, 61, 75, 68, 69, 64, 75, 73, 72, 82, 76, 74, 77.
Group the data first in discontinuous class intervals such that one of the class intervals is 70-74.
Next, group the data in continuous class intervals such that one of the class intervals is 85-90.
Find the second class interval and the corresponding frequency of the class for both the groupings of the data.

Answer 1

Discontinuous class intervals
$\begin{array}{cc}\text{Class interval}& \text{Frequency}\\ 60-64& 4\\ 65-69& 6\\ 70-74& 7\\ 75-79& 7\\ 80-84& 8\\ 85-89& 8\end{array}$
Continuous class intervals
$\begin{array}{cc}\text{Class interval}& \text{Frequency}\\ 61-65& 4\\ 65-70& 6\\ 71-75& 7\\ 75-80& 7\\ 81-85& 8\\ 85-90& 8\end{array}$

From the frequency distribution tables, it can be inferred that,

The second class interval for the discontinuous frequency distribution table is 65 - 69 and the corresponding frequency of the class are 6.

While the second class interval for the continuous frequency distribution table is 65 - 70 and the corresponding frequency of the class is 6.