In: Statistics and Probability
Question I
In the senior year of a high school graduating class of 100
students, 42 studied mathematics, 68 studied psychology, 54 studied
history, 22 studied both mathematics and history, 25 studied both
mathematics and psychology, 7 studied history but neither
mathematics nor psychology, 10 studied all three subjects, and 8
did not take any of the three. Randomly select a student from the
class and find the probabilities of the following events.
(a) A person enrolled in psychology takes all three subjects.
(b) A person not taking psychology is taking both history and
mathematics
A
The probability that an automobile being filled with gasoline also
needs an oil change is 0.25; the probability that it needs a new
oil filter is 0.40; and the probability that both the oil and the
filter need changing is 0.14.
(a) If the oil has to be changed, what is the probability that a
new oil filter is needed?
(b) If a new oil filter is needed, what is the probability that the
oil has to be changed?