Assume that 20 percent
of students have taken calculus in high school. Of those who have
taken calculus in high school, 65 percent
plan to major in science. Of those who did not take calculus in high school,
only 25 percent plan to major in science.



What is the probability that a randomly selected student
plans to major in science?

Draw a probability tree to help you.

Then, the probability that a student planning to major in science is given by: