On a five question multiple choice test there are five possible answers of which one is correct. If a student guesses randomly and independ

Question

On a five question multiple choice test there are five possible answers of which one is correct. If a student guesses randomly and independently what is the probability that she is correct only on two questions?​

in progress 0
Bình An 4 years 2021-08-22T05:12:09+00:00 1 Answers 17 views 0

Answers ( )

  1. Orla
    0
    2021-08-22T05:13:37+00:00
    Reply

    Answer:

    The probability that she is correct on only two questions is 0.246

    Explanation:

    The probability of getting an answer correct = 1/5

    The probability of getting only two questions correctly

    By binomial trials, we have;

    P(X = K) = \dbinom{n}{k}\times p^{k}\times \left (1 - p \right )^{n - k}

    P(X = 2) = \dbinom{6}{2}\times \left (\dfrac{1}{5} \right )^{2}\times \left (1 - \dfrac{1}{5} \right )^{6 - 2}

    = 15×256/15625 = 768/3125 = 0.246

    Therefore, the probability that she is correct on only two questions = 0.246.

Leave an answer

Browse

Giải phương trình 1 ẩn: x + 2 - 2(x + 1) = -x . Hỏi x = ? ( )