To answer this, the total number of questions on the test would need to be known.
The probability is indeterminate. I might ask a student or I might not.
1/2.
To find the probability of getting at least 6 correct answers on a 10-question multiple-choice exam where each question has 5 choices (with only one correct answer), we can model this situation using the binomial probability formula. The probability of guessing correctly on each question is ( p = \frac{1}{5} ) and incorrectly is ( q = \frac{4}{5} ). We need to calculate the sum of probabilities for getting exactly 6, 7, 8, 9, and 10 correct answers. Using the binomial formula, the probability ( P(X = k) ) for each ( k ) can be computed, and then summed to find ( P(X \geq 6) ). The resulting probability is approximately 0.0163, or 1.63%.
The probability this student will fail is the same as the probability that some other student will flip a fair coin 20 times and get less than 8 heads, i.e., more than 12 tails. There are 2^20 possible different-looking sequences of 20 coinflips, which we assume all have equal probability. Of those sequences, 1 has no heads at all, 20 have exactly 1 head, 190 have exactly 2 heads, ... and 77520 have exactly 7 heads. So we sum up all those possible ways to fail and we get ... ... ... I'm assuming that the student answers randomly, flipping a fair (50:50) coin on each question to choose "true" or "false". In that special case, it doesn't matter how many of those twenty questions are true or how many are false. (If the student answers randomly by flipping an unfair coin, say a 25:75 coin, then it does matter how many of those questions are true -- I'll let you figure that one out).
Probability of picking a student is 800 / (800+50+150) = 800 / 1000 = .8.
The probability is indeterminate. I might ask a student or I might not.
What is the probability of what?Guessing them all correctly?Getting half of the correct?Getting them all wrong?PLEASE be specific with your questions if you want WikiAnswers to help.
The probability of getting at least 1 answer correct = 1 - Probability of getting all answers correct.So in your case it for be P(at least 1 answer correct) = 1 - 1/256where 256 is your sample space, |S| = 2^8.
If a student is picked at random what is the probability that he/she received an A on his/her fina?
2
1/2.
To find the probability of getting at least 6 correct answers on a 10-question multiple-choice exam where each question has 5 choices (with only one correct answer), we can model this situation using the binomial probability formula. The probability of guessing correctly on each question is ( p = \frac{1}{5} ) and incorrectly is ( q = \frac{4}{5} ). We need to calculate the sum of probabilities for getting exactly 6, 7, 8, 9, and 10 correct answers. Using the binomial formula, the probability ( P(X = k) ) for each ( k ) can be computed, and then summed to find ( P(X \geq 6) ). The resulting probability is approximately 0.0163, or 1.63%.
The probability this student will fail is the same as the probability that some other student will flip a fair coin 20 times and get less than 8 heads, i.e., more than 12 tails. There are 2^20 possible different-looking sequences of 20 coinflips, which we assume all have equal probability. Of those sequences, 1 has no heads at all, 20 have exactly 1 head, 190 have exactly 2 heads, ... and 77520 have exactly 7 heads. So we sum up all those possible ways to fail and we get ... ... ... I'm assuming that the student answers randomly, flipping a fair (50:50) coin on each question to choose "true" or "false". In that special case, it doesn't matter how many of those twenty questions are true or how many are false. (If the student answers randomly by flipping an unfair coin, say a 25:75 coin, then it does matter how many of those questions are true -- I'll let you figure that one out).
Probability of picking a student is 800 / (800+50+150) = 800 / 1000 = .8.
15%? (My math sucks - I probably got that wrong).
If there are four possible answers to a question, then a guessed answer would have a probability of 1 in 4. If there are six questions, then the mean number of correct answers would be six times 1 in 4, or 1.5
The probability is 0.5