Statistics Algebra

A quality control researcher at an electronics company is testing the life of the company's batteries in a certain camera. The researcher selects 100 batteries at random from the daily output of the batteries and finds that the life of the batteries has a mean of 342 pictures with an associated margin of error of 18 pictures. Which of the following is the most appropriate conclusion based on their data?

• All the batteries produced by the company that day have a life between 324 and 360 pictures.
• All the batteries ever produced by the company have a life between 324 and 360 pictures.
• It is plausible that the mean life of batteries produced by the company that day is betweeen 324 and 360 pictures.
• It is plausible that the mean life of all the batteries ever produced by the company is between 324 and 360 pictures.

A research assistant randomly selected 75 undergraduate students from the list of all students enrolled in the psychology degree program at a large university. She asked each of the 75 students, "How many minutes per day do you typically spend reading?" The mean reading time in the sample was 89 minutes and the margin of error for the estimate was 4.28 minutes. Another research assistant intends to replicate the survey and will attempt to get a smaller margin of error. Which of the following samples will most likely result in a smaller margin of error for the estimated mean time students in the psychology degree program read per day?

• 40 randomly selected undergraduate psychology degree program students.
• 40 randomly selected undergraduate students from all degree programs at the college.
• 300 randomly selected undergraduate psychology degree program students.
• 300 randomly selected undergraduate students from all degree programs at the college.

The average (arithmetic mean) of 1, 2, 5, 9, and x is 4. The average (arithmetic mean) of 2, 3 and y is 6. What is the value of x + y?

• 3
• 10
• 13
• 16

Tags

CCSS.6.EE.B.7

Two classes were given a math test. The first class had 25 students and the average test score was 86%. The second class had 15 students and their average score was 94%. If the teacher combined the test scores of both classes, what is the average of both classes together?

• 88%
• 89%
• 90%
• 91%

Tags

CCSS.7.NS.A.3

The first metacarpal bone is located in the wrist. The scatterplot below shows the relationship between the length of the first metacarpal bone and height for 9 people. The line of best fit is also shown.
How many of the people have an actual height that differs by more than 3 cm from the height predicted by the line of best fit?

• 2
• 4
• 6
• 9

The table below classifies 103 elements as metal, metalloid, or nonmetal and as solid, liquid, or gas at standard temperature and pressure.
What fraction of all solids and liquids in the table are metalloids?

• 7/92
• 7/90
• 7/103
• 78/92

In the figure, WXYS is a square, as are SYTV and RVUS. If a point is selected at random from WXYZ, what is the probability that the point is in one of the shaded regions?

• 2/5
• 15/32
• 12/25
• 1/2

A store is deciding whether to install a new security system to prevent shoplifting. Based on store records, the security manager of the store estimates that 10,000 customers enter the store each week, 24 of whom will attempt to shoplift. Based on data provided from other users of this security system, the manager estimates the results of the new security system is detecting shoplifters will be shown in the table.
According to the manager's estimates, if the alarm sounds for a customer, what is the probability that the customer did not attempt to shoplift?

• .03%
• .035%
• .56%
• 62.5%

The histogram summarizes the distribution of time worked lst week in hours by the 40 employees of a landscaping company. In the histogram, the first bar represents all workers who worked at least 10 hours but less than 20 hours, the second represents all workers who worked at least 20 hours but less than 20 hours and so on. Which of the following could be the median and mean amount of time worked in hours for the 40 employees?

• Median = 22, Mean = 23
• Median = 24, Mean = 22
• Median = 26, Mean = 32
• Median = 32, Mean = 30

The dot plots show the distribution of scores on a current events quiz for two classes of 24 students. Which of the following correctly compares the standard deviation of the scores in each of the classes?

• The standard deviation of quiz scores in class A is smaller.
• The standard deviation of quiz scores in class B is smaller.
• The standard deviation of quiz scores in class A and class B are the same.
• The relationship cannot be determined by the given information.