Exam 2: Descriptive Statistics

Consider a sample on the waiting times (in minutes) at the billing counter in a grocery store to be 15, 24, 18, 15, 21, 20, 15, 22, 19, 16, 15, 22, 20, 15, and 21. Compute the 25th, 50th, and 75th percentiles.

The scores of a sample of students in a Math test are 20, 15, 19, 21, 22, 12, 17, 14, 24, 16 and in a Stat test are 16, 12, 19, 17, 22, 14, 20, 21, 24, 15, 13. a. Compute the mean and median scores for both the Math and the Stat tests. b. Compare the mean and median scores computed in part a. Comment.

For the following sample data, compute the variance. 32 41 36 24 29 30 40 22 25 37

A variable whose values are not known with certainty is called a _____.

The mentor of a class researched on the number of hours spent on study in a week by each student of the class, to analyze the correlation between the study hours and the marks obtained by each student. The data on the hours spent per week by 25 students are listed below: a. What is the least amount of time a student spent per week on studying after school hours in this sample? The highest? b. Use a class width of 2 hours to prepare a frequency distribution, a relative frequency distribution, and a percent frequency distribution for the data. c. Prepare a histogram and comment on the shape of the distribution.

Compute the median of the following data: 32 41 36 24 29 30 40 22 25 37

_____ are collected from several entities at the same point in time.

Compute IQR for the following data. 10 15 17 21 25 12 16 11 13 22

Consider the following data on income and savings of a sample of residents in a locality: a. Compute the correlation coefficient. Is there a positive correlation between the income and savings? What is your interpretation? b. Show a scatter diagram of the relationship between the income and savings.

The purpose of using enough bins is to show the

The _____ shows the number of data items with values less than or equal to the upper class limit of each class.

Compute the mean of the following data: 56 42 37 29 45 51 30 25 34 57

In a(n) _____, one or more variables are identified and controlled or manipulated so that data can be obtained about how they influence the variable of interest identified first.

The results of a survey showed that on average, children spend 5.6 hours at PlayStation per week. Suppose that the standard deviation is 1.7 hours and that the number of hours at PlayStation follows a bell-shaped distribution. a. Use the empirical rule to calculate the percentage of children who spend between 2.2 and 9 hours at PlayStation per week. b. What is the z-value for a child who spends 7.5 hours at PlayStation per week? c. What is the z-value for a child who spends 4.5 hours at PlayStation per week?

The data on the time taken by₁₀ students in a class to answer a test is an example of

Compute the mode for the following data: 12 16 19 10 12 11 21 12 21 10

Compute the coefficient of variation for the following sample data. 32 41 36 24 29 30 40 22 25 37

When the data are large and when it is difficult to analyze all at once, which of the following feature in Excel is used to make the data more manageable and to develop insights?

Compute the third quartile for the following data. 10 15 17 21 25 12 16 11 13 22

The simplest measure of variability is the