Question

rosa’s work finding the median of a set of test scores is shown below.
{80, 70, 90, 80, 90, 65, 100, 100, 90}
90
which statement best describes rosas first error?
○ she should have reordered the elements from least to greatest.
○ she should have added the elements and divided by 9.
○ she should have counted repeated elements only once.
○ she should have found the difference between the first and last elements.

Explanation:

To find the median, the first step is to order the data set from least to greatest. Rosa's data set \(\{80, 70, 90, 80, 90, 65, 100, 100, 90\}\) is not ordered. The second option describes finding the mean, not median. The third option is incorrect as repeated elements are included in the data set and should be counted. The fourth option describes finding the range, not median. So the first error is not reordering from least to greatest.

Answer:

A. She should have reordered the elements from least to greatest.