A student has a probability of having an incorrect answer of .1. The student takes a test
with 25 questions. Each question is worth 4 points. An A is a 92 or better. What is the
probability that the student receives an A? What is the student’s expected score?

Question

A student has a probability of having an incorrect answer of .1. The student takes a test
with 25 questions. Each question is worth 4 points. An A is a 92 or better. What is the
probability that the student receives an A? What is the student’s expected score?

anonymous · Answer

Try finding the expected score first: if Pr(incorrect)=0.1, then Pr(correct)=0.9.
You can multiply that by the number of questions to get the expected number correct, then multiply that by 4 to get the expected points.

Understand?

anonymous · Answer

I believe so. From what you just wrote, the students expected score is 90. And the if we were to try to find the probability of the student achieving an A, would it be 13% - if p=.1, n=25, and x=4.. using bionmcdf( 25, .1, 4) = .13 Is this correct?