A student knows correct answers to 10 questions out of 12 questions from the book. (A) If a professor asks 9 questions from the book, what is the probability that a student knows correct answers to more than 7 of these questions? (B) Let X be the number of questions that can be answered correctly by the student from a sample of 9 questions asked by the professor. Find the mean and the standard deviation of X.
A student knows correct answers to 10 questions out of 12 questions from the book. (A) If a professor asks 9 questions from the book, what is the probability that a student knows correct answers to more than 7 of these questions? (B) Let X be the number of questions that can be answered correctly by the student from a sample of 9 questions asked by the professor. Find the mean and the standard deviation of X.
A First Course in Probability (10th Edition)
10th Edition
ISBN:9780134753119
Author:Sheldon Ross
Publisher:Sheldon Ross
Chapter1: Combinatorial Analysis
Section: Chapter Questions
Problem 1.1P: a. How many different 7-place license plates are possible if the first 2 places are for letters and...
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Transcribed Image Text:A student knows correct answers to 10 questions out of 12
questions from the book.
(A) If a professor asks 9 questions from the book, what is the probability
that a student knows correct answers to more than 7 of these
questions?
(B) Let X be the number of questions that can be answered correctly by the
student from a sample of 9 questions asked by the professor. Find the
mean and the standard deviation of X.
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