Probability
posted by Student .
Darby guesses the answers to six questions on the math portion of her college entrance exam. Each question is a true or false question. What is the approximate probability that at least 4 of her answers are correct?
A. 0.23
B. 0.34
C. 0.66
D. 0.78
Explanation please??

The answer is
(n,r)/2^n
Here there are 6 questions, so n=6, and
there are 2^6=64 possible sets of answers.
Since 4 of them are right, the number of combinations with 4 correct out of 6 is
(n,r)=(6,4)=6*5/(1*2)=15
What would be the probability that 4 out of six are correct if the answers are completely random?
Respond to this Question
Similar Questions

Math
Darby guesses the answers to six questions on the math portion of her college entrance exam. Each question is a true or false question. What is the approximate probability that at least 4 of her answers are correct? 
Math
Darby guesses the answers to six questions on the math portion of her college entrance exam. Each question is a true or false question. What is the approximate probability that at least 4 of her answers are correct? 
Probability
Darby guesses the answers to six questions on the math portion of her college entrance exam. Each question is a true or false question. What is the approximate probability that at least 4 of her answers are correct? 
Probability
Thank you for the explanation MathMate! Would the answer to this question be A? 
Maths
A true/ false test is given. If a person guesses the answers, the probability that any particular question is correctly answered is 0.5. If the test contains 14 questions and 7 correct answers is a pass, what is the probability of … 
Statistical concept 689599.7
1. A student taking a midterm exam in Ancient History comes to two questions pertaining to a lecture that he missed, and so he decides to take a random guess on both questions. One question is truefalse and the other is multiple choice … 
Stat HW for.
1. A student taking a midterm exam in Ancient History comes to two questions pertaining to a lecture that he missed, and so he decides to take a random guess on both questions. One question is truefalse and the other is multiple choice … 
Statistics Algebra 2
A 10question multiple choice test has 4 possible answers for each question. A student guesses on all ten answer. a)What is the probability that the student selects at least 6 correct answers? 
Math
There are six truefalse questions on a quiz. Not knowing any of the answers, a student guesses randomly. Find the probability of each event. Exactly two answers are correct. Exactly six answers are correct. At least five are correct. … 
Math
A student randomly guesses the answers to a four question true or false quiz. Find the probability that the student answers F on at least 2 of the questions