A study of education followed a large group of fifth-grade children to see how many years of school that a randomly chosen fifth grader completes. Let X be the highest year of school that a randomly chosen fifth grader completes. (Students who go on to college are included in the outcome X = 12.) The study found the probability distribution of X:

Years 4 5 6 7 8 9 10 11 12
Prob. 0.010 0.007 0.007 0.013 0.032 0.068 0.070 0.041 0.752

a. What percent of fifth graders eventually finished twelfth grade?
b. Check that this is a legitimate probability distribution.
c. Find R(X >=26).
d. Find (PX>6).
e. What values of X make up the event "the student completed at least one year of high school? (High school begins with the ninth grade.) What is the probability Of this event?