SOLUTION: 1. A student has to sit for an examination consisting of 3 questions selected
at random from a list of 100 questions. To pass, he needs to answer all
three questions. What is the
Algebra.Com
Question 836121: 1. A student has to sit for an examination consisting of 3 questions selected
at random from a list of 100 questions. To pass, he needs to answer all
three questions. What is the probability that the student will pass the
examination if he knows the answers to 90 questions on the list?
2. Two fair dice are rolled and the outcome is kept secret. You are vitally
interested in the sum shown.
(a) What is the probability that the sum will be at least 5?
(b) Suppose that at least one die shows 1, how likely is it now that the
sum will be 5 or more?
Answer by stanbon(75887) (Show Source): You can put this solution on YOUR website!
1. A student has to sit for an examination consisting of 3 questions selected
at random from a list of 100 questions. To pass, he needs to answer all
three questions. What is the probability that the student will pass the
examination if he knows the answers to 90 questions on the list?
----
Binomial Problem with n = 3 and p(correct) = 0.9
P(x = 3) = 0.9^3 = 0.729
----------------------------------------
2. Two fair dice are rolled and the outcome is kept secret. You are vitally
interested in the sum shown.
(a) What is the probability that the sum will be at least 5 ?
Ans: P(x >=5) = 1 - P(2<= x <=4) = 1 - (6/36) = 30/36
----
(b) Suppose that at least one die shows 1, how likely is it now that the
sum will be 5 or more?
Note: The number on a face is ALWAYS "at least 1".
Ans: same as "a": 30/36
=============================
Cheers
Stan H.
==================
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