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I need help quick! please!

Assume that random guesses are made for nine multiple choice questions on an SAT​ test, so that there are nequals9 ​trials, each with probability of success​ (correct) given by pequals0.35. Find the indicated probability for the number of correct answers.
Find the probability that the number x of correct answers is fewer than 4.

P(x<4)= ???

User Iakobski
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1 Answer

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Answer: the probability that the number x of correct answers is fewer than 4 is 0.61

Explanation:

Let x be a random variable representing the answers to the SAT questions. This is a binomial distribution since the outcomes are two ways. It is either the answer is correct or incorrect. Also, the probability of success or failure is constant for each trial. The probability of success, p = 0.35

The probability of failure, q would be 1 - p = 1 - 0.35 = 0.65

We want to determine P(x < 4)

n = number of trial = 9

x = 4

From the binomial distribution calculator,

P(x < 4) = 0.61

User Dico
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