The final mathematics exam at a certain school contains questions of equal difficulty and is matched to the students' past performance in mathematics. Four students who take the exam have averages 25%, 50%, 60%, and 80%. What is the probability that at least one of these students will get the first question on the exam correct?

A) 97/100

B) 9/10

C) 17/20

D) 13/15

E) 23/30

jonathanxu999
Jan 13, 2018