7:5 is equivalent to 21: ?
2 answers:
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Answer:
The teacher should set the score 7 as the lowest passing grade.
Step-by-step explanation:
Let <em>X</em> = number of correct guesses.
All the questions are of true-false format.
The probability of getting a correct answer is, <em>p</em> = 0.50.
The total number of questions is, <em>n</em> = 10.
The random variable <em>X</em> follows a Binomial distribution with parameters <em>n</em> = 10 and <em>p </em>= 0.50.
The probability mass function of <em>X</em> is:
Now the teaches chose the grading scheme such that the probability of passing a student who guesses on every question is less than 0.05.
Then the probability of failing such a students is at least 1 - 0.05 = 0.95.
Compute the probability distribution of <em>X</em>.
Consider the probability distribution attached below.
The value of <em>x</em> for which P (X ≤ x) is at least 0.95 is, <em>x</em> = 7.
So the teacher should set the score 7 as the lowest passing grade.
