Exam 2: Methods for Describing Sets of Data

Percentile rankings are of practical value only with large data sets.

The sample variance is always greater than the sample standard deviation.

For the distribution drawn here, identify the mean, median, and mode.

The mean $\bar { x }$ of a data set is 18 , and the sample standard deviation s is 2 . Explain what the interval (12,24) represents.

The scatterplot below shows a negative relationship between two variables.

At the U.S. Open Tennis Championship a statistician keeps track of every serve that a player hits during the tournament. The statistician reported that the mean serve speed of a particular player Was 96 miles per hour (mph)and the standard deviation of the serve speeds was 9 mph. Using the Z-score approach for detecting outliers, which of the following serve speeds would represent Outliers in the distribution of the playerʹs serve speeds? Speeds: 65 mph, 105 mph, and 114 mph

A study was designed to investigate the effects of two variables -(1)a studentʹs level of mathematical anxiety and (2)teaching method - on a studentʹs achievement in a mathematics course. Students who had a low level of mathematical anxiety were taught using the traditional expository method. These students obtained a mean score of 300 and a standard deviation of 50 on a standardized test. Find and interpret the z-score of a student who scored 440 on the standardized test.