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

The conditional - relative frequencies for 8th and 9th graders are different for using and not - using social media, so there is an association. So the statement "There is no association between using social media and grade level" and "Knowing a student’s grade level does not help determine if he or she uses social media" are false.

Step2: Check 9th - grade probability

The conditional relative frequency of a 9th - grader using 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: Compare non - use probabilities

The conditional relative frequency of an 8th - grader not using social media is 0.16 and for a 9th - grader 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 likelihood

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

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.