Question

The dot plots below show the ages of students belonging to two groups of painting classes:

Based on visual inspection, which group most likely has a lower mean age of painting students? Explain your answer using two or three sentences. Make sure to use facts to support your answer.

Answer 1

this is the dot plots

Answer 2

add up all of the dots, then divide by the number of dots

Answer 3

No need to waste your time and find the mean of each graph.

Mean has absolutely no statistical resistance as compared to the median. What this means is that skewed data is easily impacted by means, while clustered data is less impacted by means.

Group B's graph is skewed to the right. There is a cluster around 10-20 but the graph is approximately multimodal and has another cluster from 25-30. This will pull the mean towards 25-30.
Group A graph is slightly skewed to the left but is not as extreme and as compared to group B, it can be seen as a central cluster. This means that the mean of Group A's data is not as great as the mean of group B.

Hope that helps.

Answer 4

A helpful tip:

Mean has no statistical resistance. Median has strong statistical resistance. Median is better to use with skewed graphs. Mean is better to use with bell curve graphs.

Standard deviation and range have minimal statistical resistance. IQR has the greatest statistical resistance. Their uses are respective to that of Mean and median.