(1 point) North Carolina State University posts the grade distributions for its
ID: 3337298 • Letter: #
Question
(1 point) North Carolina State University posts the grade distributions for its courses online. Students in Statistics 101 in the Fall 2007 semester received 26% A's, 42% B's, 20% C's, 10% D's, and 2% FS. Choose a Statistics 101 student at random. To "choose at random" means to give every student the same chance to be chosen. The student's grade on a four-point scale (with A = 4) is a discrete random variable X with this probability distribution: Value of X 0 2 4 Probability 0.02 0.10 0.20 0.42 0.26 (a) What values of random variable X are represented by the event "the student got a grade poorer than B"? Write your answer as a comma-separated list. (b) What is the probability of the event from part (a)?Explanation / Answer
Ans:
a)X will take values 0,1,2 for the event that the student got a grade poorer than B.
b)Probability that the student got a grade poorer than B
=P(x=0)+P(x=1)+P(2)
=0.02+0.1+0.2
=0.32
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