if 70% teenagers take a test-those who studied 95%pass-those who did not study 60% pass-what is the probability that a randomly selected teenage will pass
I guess you mean that 70% studied?
If so then if there were 100 students:
70 studied, 66.5 passed
30 did not study, 18 passed
so out of 100 students 84.5 pass
so .845