an examination ,60% of the candidates failed the number of candidates who passed was 500 .find the number that failed
1 answer:
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Answer:
we can set the 9 as a benchmark to be the score for the passing grade so that probability of passing a student who guesses every question is less than 0.10
Step-by-step explanation:
From the given information;
Sample size n = 12
the probability of passing a student who guesses on every question is less than 0.10
In a alternative - response question (true/false) question, the probability of answering a question correctly = 1/2 = 0.5
Let X be the random variable that is represent number of correct answers out of 12.
The X BInomial (12, 0.5)
The probability mass function :
P(X = 12) = 2.44 × 10⁻⁴
P(X =11 ) = 0.00293
P(X = 10) = 0.01611
P(X = 9) = 0.0537
P(X = 8) = 0.12085
P(X = 7) = 0.19335
.........
We can see that,a t P(X = 9) , the probability is 0.0537 which less than 0.10 but starting from P(X = 8) downwards the probability is more than 0.01
As such, we can set the 9 as a benchmark to be the score for the passing grade so that probability of passing a student who guesses every question is less than 0.10