Question

Exam Scores. The exam scores for the students in an introductory statistics class are as follows.

a. Group these exam scores, using the classes $30-39,40-49,50-59,60-69,70-79,80-89$, and $90-100$.

b. What are the widths of the classes?

c. If you wanted all the classes to have the same width, what classes would you use?

Short answer

a). The group of distribution is,

$\begin{array}{rr}\text{Class}& \text{Frequency}\\ 30-39& 2\\ 40-49& 0\\ 50-59& 0\\ 60-69& 3\\ 70-79& 3\\ 80-89& 8\\ 90-100& 4\end{array}$

b). With the exception of the last class, which has a width of $10$, all of the classes have a width of $9$.

c). The last class need to be replaced by the two classes $99-90$and $100-109$.

Step-by-step solution

Part (a) Step 1: Given Information

The data is given as,

Part (a) Step 2: Explanation

The group distribution is,

$\begin{array}{rr}\text{Class}& \text{Frequency}\\ 30-39& 2\\ 40-49& 0\\ 50-59& 0\\ 60-69& 3\\ 70-79& 3\\ 80-89& 8\\ 90-100& 4\end{array}$

Part (b) Step 1: Given Information

The data is given is,

Part (b) Step 2: Explanation

With the exception of the last class, which has a width of $10$, all of the classes have a width of $9$.

Part (c) Step 1: Given Information

The data is given as,

Part (c) Step 2: Explanation

The last class need to be replaced by the two classes $99-90$ and $100-109$.