Random Samples with Dot Plots

The dot plots show how long it took students in Mr. Chauncey's two science classes to finish their science homework last night. Find the means to make an inference about the data.

• The 1st period mean is 35. The 2nd period mean is 38.75. On average, it took students in the 1st period class slightly longer to finish their homework than it did the students in the 2nd period class.

• The 1st period mean is 38.75. The 2nd period mean is 35. On average, it took students in the 1st period class slightly longer to finish their homework than it did the students in the 2nd period class.

• The 1st period mean is 35. The 2nd period mean is 38.75. On average, it took students in the 2nd period class slightly longer to finish their homework than it did the students in the 1st period class.

• The 1st period mean is 38.75. The 2nd period mean is 35. On average, it took students in the 2nd period class slightly longer to finish their homework than it did the students in the 1st period class.

The dot plot shows a random sample of the number of fish caught and released by 30 participants during a two-day fishing tournament. Select the inference that can be made based on the data collected.

• On average, most participants caught and released 5 or more fish.

• More participants caught 6 fish than any other number.

• The same participants who caught and released 1 fish the first day caught and released 1 fish on the second day.

• On average, participants caught and released more fish on Day 2.

If you compare the medians of each data set, who spends more time online?

• Seventh graders

• Eight graders

• Both grades spend an equal amount of time online.

• Impossible to determine form the data sets.

A quality inspector is testing the packaging of jars of kimchi produced by Korean Snacks, Inc. and Park Food, LTD. Ten random samples of 250 jars of kimchi are used for the inspection. The dot plots show the number of jars with failed packaging for each sample. In a production run of 10,000 jars of kimchi from each brand, what difference in the number of jars with failed packaging would be expected between the brands?

• Based on the samples, the mean number of jars of kimchi that failed in inspection for Korean Snacks, Inc. is 4.6, and for Park Foods, Ltd is 5. The difference between the expected number of packaging failures for 10,000 jars from each of the two companies would be 20 jars.

• Based on the samples, the mean number of jars of kimchi that failed in inspection for Korean Snacks, Inc. is 4.6, and for Park Foods, Ltd is 4.8. The difference between the expected number of packaging failures for 10,000 jars from each of the two companies would be 8 jars.

• Based on the samples, the mean number of jars of kimchi that failed in inspection for Korean Snacks, Inc. is 4.5, and for Park Foods, Ltd is 4.8. The difference between the expected number of packaging failures for 10,000 jars from each of the two companies would be 10 jars.

• Based on the samples, the mean number of jars of kimchi that failed in inspection for Korean Snacks, Inc. is 4, and for Park Foods, Ltd is 5. The difference between the expected number of packaging failures for 10,000 jars from each of the two companies would be 40 jars.

A box contains 90 letter tiles used for a word game. Fourteen students each select a random sample of 20 letters from the box, count the vowels, and return the sample to the box. The dot plot shows their results. What is the best estimate for the number of vowels in the box? Round the final answer to the nearest whole number.

• 38.25

• 39

• 38

• 8.5

The dot plots show the number of plastic bottles and aluminum cans students collected each day over a 15 day period. What is the median number of items the students collected and the IQR?

• Plastic Bottles: median=18 IQR=5

• Aluminum Cans: median=13 IQR=4

• Plastic Bottles: median=18 IQR=8

• Aluminum Cans: median=13 IQR=6

Which pair of data sets would show the least visual overlap when plotted on dot plots?

• Data set A: mean: 25, MAD: 3

  Data set B: mean: 25, MAD: 4

• Data set A: mean: 40, MAD: 2

  Data set B: mean: 40, MAD: 5

• Data set A: mean: 15, MAD: 4

  Data set B: mean: 15, MAD: 6

• Data set A: mean: 50, MAD: 5

  Data set B: mean: 50, MAD: 9

The dot plots show the number of cheese and pepperoni pizzas that were sold each day over a 15-day period. What is the median and IQR of cheese and pepperoni pizzas sold?

• Cheese Pizza: Median=32 IQR=4

• Cheese Pizza: Median=30 IQR=4

• Pepperoni Pizza: Median=24 IQR=5

• Pepperoni Pizza: Median=22 IQR=5

Dylan measured the heights of 40 trees on a college campus. He used a random sample of 20 trees in direct sunlight and 20 trees in shade. The dot plots show the heights of the trees in each sample. Which inferences can Dylan make based on the dot plots?

• The trees in the shade have less consistent heights and generally do not grow as tall as the trees in the direct sunlight.

• The trees in the shade have less consistent heights and generally grow taller than the trees in the direct sunlight.

• The trees in the shade have more consistent heights and generally do not grow as tall as the trees in the direct sunlight.

• The trees in the shade have more consistent heights and generally grow taller than the trees in the direct sunlight.

The bag contains 81 quarters. Twelve students each select a random sample of 16 quarters from the bag, count the number of quarters with a date before 2000, and return the sample to the bag. The line plot shows their results. Which is the best estimate for the number of pre-2000 quarters in the bag, to the nearest whole number?

• 21

• 28

• 30

• 37