Suppose that for a randomly selected high school student who has taken a college entrance exam, the probability of scoring above 650 is 0.30. A random sample of n = 9 students was selected. The probability that at exactly of the students scored over 650 points is found using:

The formula to compute the probability that at exactly x of the students scored over 650 points is:

Step-by-step explanation:

Let the random variable X represent the number of students who scored above 650 in the college entrance exam.

The probability that a student scored above 650 in the college entrance exam is, p = 0.30.

A random sample of n = 9 students was selected.

The events of any student scoring above 650 in the college entrance exam  is independent of the others.

The random variable X follows a Binomial distribution with parameters n = 9 and p = 0.30.

The probability mass function of X is:

Thus, the formula to compute the probability that at exactly x of the students scored over 650 points is:

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step-by-step explanation: