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)= ???

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

Step-by-step 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

If the shapes are similar, the correspondent sides are in proportion:

Let's plug the values and solve for x:

Multiply both sides by x to get

The only feasible solution, though, is , because it wouldn't make sense to have negative lengths.