SOLUTION: Several students are unpreapred for a surprise true/false test with 9 questions and all of their answers are guesses. Find the mean and standard deviation for the number of correc
Algebra ->
Probability-and-statistics
-> SOLUTION: Several students are unpreapred for a surprise true/false test with 9 questions and all of their answers are guesses. Find the mean and standard deviation for the number of correc
Log On
Question 506626: Several students are unpreapred for a surprise true/false test with 9 questions and all of their answers are guesses. Find the mean and standard deviation for the number of correct answers. Would it be unusual for a student to p[ass by guessing and getting at least 4 correct answers? Answer by stanbon(75887) (Show Source):
You can put this solution on YOUR website! Several students are unpreapred for a surprise true/false test with 9 questions and all of their answers are guesses. Find the mean and standard deviation for the number of correct answers. Would it be unusual for a student to pass by guessing and getting at least 4 correct answers?
----
Binomial Problem with n = 9 and p = 1/2
----
mean = np = 9*(1/2) = 4.5
std = sqrt(npq) = sqrt[2.25] = 1.5
----
P(4<= x <=9) = 1-P(0<= x <=3) = 0.7461
=========================================
Cheers,
Stan H.
==========
(