Lesson 27 making statistical Inferences

Marta believes it will be easier to identify clusters of data if the results are represented with a dot plot. Do you agree?

• Yes. In a dot plot, the more frequently occurring results will appear as taller stacks of dots.

• No. In a dot plot, the more frequently occurring results will appear as taller stacks of dots.

A box contains 80 loose white or yellow golf balls. Each student in Mr. Koger's class drew a random sample of 20 balls from the box, counted the yellow balls, and then returned the sample to the box. Nate calculated the proportion of balls in each sample that were yellow and organized the results in a dot plot. According to the data, what is a good estimate for the number yellow balls in the box?

• 15

• 23

• 35

• 43

A box in Ms. Booth's class contains 200 loose white or yellow golf balls. The table represents the results when 11 students each drew a random sample of the same number of balls, counted the number of yellows, and then returned the sample to the box. Which graphic representation of the data would best help estimate the number of yellow balls in the box?

• Table

• Dot Plot

• Box Plot

• None of the above

Lana believes a good estimate of the number of yellow balls in the box is 70 balls. Do you agree?

• Agree. The median 0.7 which is 70% of the value.

• Disagree. The median is 0.7 and 70% of the value is 140.

Three park rangers had to report about the ways visitors use their facilities. Each ranger surveyed a sample of park visitors. Which rangers' method has the most representative sample of their visitors?

• Ranger Li surveyed 30 randomly chosen visitors to her park's information center.

• Ranger Simpson divided his park into 30 same sized zones and surveyed one randomly chosen visitor encountered in each zone.

• Ranger Patel surveyed 30 randomly chosen people who posted reviews of the park on a fishing website.

Jackson uses a random number generator to choose 20 students from each grade and asks how long they spend on homework. Niko says that Jackson's sample is bias. Do you agree?

• I disagree. Jackson has ensured that the selection of students is random and representative of the grade levels in the school.

• I agree. There are twice as many 6th grade students as 7th or 8th grade students. He should choose 30-6th graders and 15 7th graders and 15-8th graders.

The students in Mr. Walker's class want to find out about the favorite rainy day activity of their middle school's entire student population. Pam surveyed the 23 students in her 7th Grade math class. Is her sample random or biased?

• Random

• Biased

The students in Mr. Walker's class want to find out about the favorite rainy day activity of their middle school's entire student population. To find the information described in the example, Nick surveyed every 15th student who entered the school building. Is his sample random or biased?

• Random

• Biased