Question

a group of 8th and 9th graders were surveyed about whether they use social media to communicate with their friends. the results are shown below in the conditional relative frequency table by row. which conclusions can be drawn from the results of the survey? check all that apply. there is no association between using social media and grade level. the probability a student uses social media, given that he or she is in 9th grade, is 81%. a student who is more likely to not use social media is in 8th grade. an 8th grader is more likely to use social media than not. knowing a students grade level does not help determine if he or she uses social media. do not use use total 8th grade 0.16 0.84 1.00 9th grade 0.19 0.81 1.00 total 0.38 0.62 1.00

Explanation:

Step1: Analyze association claim

The conditional - relative frequencies for 8th and 9th graders are different (0.84 for 8th - grade users and 0.81 for 9th - grade users), so there is an association. So the statement "There is no association between using social media and grade level" is false.

Step2: Check 9th - grade probability

The conditional relative frequency of 9th - graders who use social media is 0.81 or 81%. So the statement "The probability a student uses social media, given that he or she is in 9th grade, is 81%" is true.

Step3: Check non - user grade

The conditional relative frequency of 8th - graders who do not use social media is 0.16 and for 9th - graders is 0.19. Since 0.16<0.19, a student who is more likely to not use social media is not in 8th grade. So the statement "A student who is more likely to not use social media is in 8th grade" is false.

Step4: Check 8th - grade usage

The conditional relative frequency of 8th - graders who use social media is 0.84, which is greater than 0.5. So an 8th - grader is more likely to use social media than not. The statement "An 8th grader is more likely to use social media than not" is true.

Step5: Analyze grade - level help

Since there is an association (from Step 1), knowing a student's grade level helps determine if he or she uses social media. So the statement "Knowing a student's grade level does not help determine if he or she uses social media" is false.

Answer:

The probability a student uses social media, given that he or she is in 9th grade, is 81%.
An 8th grader is more likely to use social media than not.