Suppose the tree diagram below represents all the students in a high school and that one of these students were chosen at random. If the student is
known to be a girl, what is the probability that the student is right-handed?
A 5/6
B 1/4
C 1/6
D 3/4
Answer is 1/4 or 83%

Twelve different video games showing substance use were observed and the duration times of game play (in seconds) are listed below. the design of the study justifies the assumption that the sample can be treated as a simple random sample. use the data to construct a 99% confidence interval estimate of μ, the mean duration of game play. 4028 4316 4816 4650 4036 5010 4833 4331 4307