Key takeaway: This grade 7 comparing populations quiz has ten multiple-choice questions about two samples and the populations behind them. Read each dot plot and box plot carefully, compute the MAD when asked, and divide the gap between centers by the spread. Only one answer is correct each time, and the explanation shows why.
Look closely at the means and the MADs, because many wrong choices swap them. A few items test why a sample must be random, which is a favorite reasoning question.
This quiz has 10 multiple-choice questions on comparing two populations. Read each dot plot and box plot carefully, compute the MAD when asked, and divide the difference of the centers by the variability. Only one answer is correct in each question.
Two random samples have means of 40 and 52. Both MADs are 4. The difference of the means is how many MADs?
Use the dot plots of goals scored.
Which statement is correct?
What does the MAD of a data set measure?
The box plots show water temperatures of two pools.
What is the difference of the medians?
Why should a sample be random when you compare two populations?
The dot plots show reaction times of two random samples.
The means are 12 and 13 seconds, and each MAD is about 1 second. What is the best conclusion?
Find the MAD of the data 2, 4, 6, 8, and 10.
Sample A has a mean of 7.8 inches and Sample B has a mean of 6.3 inches. Both MADs are 0.5 inch. The means are how many MADs apart?
The means of two samples are 20 units apart, and the difference is 4 MADs. What is the MAD?
Two random samples of students have means of 55 and 59 minutes of sleep, and both MADs are 20 minutes. Which sentence is the best informal inference?
🎉 Quiz complete!
Remember:
- Compare centers with the mean or median, and spread with the MAD or IQR.
- Difference of the means divided by the MAD tells how many spreads apart the centers are.
- The larger the multiple, the less the two distributions overlap.
- Random samples make informal inferences about the whole populations reasonable.
- Another random sample gives slightly different numbers, so conclusions stay informal.
What does the 7th grade comparing populations quiz test?
The first item gives means of 40 and 52 with MADs of 4, so the gap is 3 MADs. Another asks for the MAD of the data 2, 4, 6, 8, and 10, which is 2.4. A third gives means of 7.8 and 6.3 inches with MADs of 0.5, which is also 3 MADs.
How do you solve a grade 7 comparing populations quiz item backward?
Two sample means sit 20 units apart, and the difference is 4 MADs. Divide 20 by 4 to get a MAD of 5. Multiply back to check, since 5 times 4 returns 20.
Why does the sample need to be random?
Fair selection means every member has the same chance of being picked. That fairness makes the sample a reasonable picture of the population. A survey of only a few friends would likely miss other opinions.
How do you read a small difference?
Two samples of sleep time have means of 55 and 59 minutes, and both MADs are 20 minutes. The gap is 4, which is small next to the spread of 20. Therefore the samples overlap a lot, and the populations may well be similar.
How do you find a MAD without a calculator?
List the values and find the mean first. For 2, 4, 6, 8, and 10, the mean is 6. The distances are 4, 2, 0, 2, and 4, which total 12, and 12 divided by 5 gives 2.4. Next, use that spread to scale the gap between any two centers.
Finally, state the result in a sentence, such as the centers are three spreads apart.
Next moves after the comparison quiz
Retry each missed item and write the multiple in words, such as three spreads apart. Then compute one MAD by hand to refresh the steps. After that, work the worksheet problems on box plots to practice reading medians.
See every chapter on the Grade 7 math page.
