A quiz consists of 20 multiple-choice questions, each with 6 possible answers. For someone who makes random guesses for all of the answers, find the probability of passing if the minimum passing grade is 40 %.
A quiz consists of 20 multiple-choice questions, each with 6 possible answers. For someone who makes random gu
Need at least 8 questions right to obtain 40%--no more than 12 wrong answers.
Probability of getting a right answer is 1 out of 6.
Probability of getting n right answers is 20! x 5^(20-n) / (n! x (20-n)! x 6^20)
Summing the above formula for n=8 to 20 yields an answer of 1.125%.
A quiz consists of 20 multiple-choice questions, each with 6 possible answers. For someone who makes random gu
The probability of these yahoos giving you the correct answer and doing your homework for you accurately is 19.7%.
A quiz consists of 20 multiple-choice questions, each with 6 possible answers. For someone who makes random gu
It is the following big messy formula, which basically consists of the sum of the probabilities that the test taker gets exactly 8 right + exactly 9 right + ... + exactly 20 right.
20C8 * (1/6)^8 * (5/6)^12 +
20C9 * (1/6)^9 * (5/6)^11 +
...
20C20 * (1/6)^20 * (5/6)^0
A quiz consists of 20 multiple-choice questions, each with 6 possible answers. For someone who makes random gu
40% is passing? What school is THIS?!? Anyway...
To get 40%, the student has to get at least 8 questions right. First look at the probabiltiy of getting exactly 8 right.
Since there are 6 choices for each question, the total number of ways you could answer a test is 6^20. There are lots of ways you could get 8 right answers, as there are lots of combinations of 8 questions you can take out of the 20. In fact, there are 20!/(8!12!) = 125,970. For any given set, the probability of getting all 8 questions right is (1/6)^8 = 1 / (6^8). So the probability of getting exactly 8 right answers on the quiz is (20! / 8!12!)(1/(6^8)).
To get the probability of getting "at least 8" correct, add to this the probabiltiy of getting 9, 10, 11, etc. through 20 correct. You get
閳?[i=8閳?0] (20! / i!(20-i)!)(1 / (6^8) =
(1/6^8) 閳?[i=8閳?0] (20! / i!(20-i)!)
Calculate this out to get the answer
A quiz consists of 20 multiple-choice questions, each with 6 possible answers. For someone who makes random gu
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