Question

Medical treatment will cure about 87% of all people who suffer from a certain eye disorder. Suppose a large medical clinic treats 57 people with this disorder. Let r be a random variable that represents the number of people that will recover. The clinic wants a probability distribution for r. Use the normal approximation to the binomial distribution.

Answers

  1. Answers to all the questions using binomial distribution are shown below.

    What is Binomial distribution?

    • The binomial distribution is a discrete probability distribution that indicates the likelihood of success in a replacement experiment.
    • This is in contrast to the Hypergeometric distribution, which provides the likelihood of success in an experiment conducted without replacement.
    To answer all the questions using binomial distribution:
    (A) The binomial distribution will be roughly normally distributed if the following conditions are satisfied:
    • np > 5
    • n(1−p ) > 5
    Given that;
    • n = 57
    • p = 0.87
    Test whether the conditions are satisfied:
    • np:57 × .87>5
    • n(1-p) : 57(1−.87)>5
    Since the conditions are satisfied, the distribution is approximately normal.
    (B) Calculate mean and standard deviation of binomial distribution:
    • E(x)=μ=np
    • = 57×.87
    • = 49.59
    • σ =√np(1−p)
    • =√57×.87(1−.87)
    • = 2.539
    Now use normal approximation:
    • P(r≤47) = P(X−μ/σ≤47−49.59/2.539)
    • = P(z≤−1.02)
    • = 0.1539
    (C)
    • P(47 ≤ r ≤ 55) = P(47 − 49.59 / 2.539 ≤ X – μ / σ ≤ 55 − 49.59 / 2.539)
    • = P(−1.02 ≤ z ≤ 2.13)
    • = P(z < 2.13)−P(z < −1.02)
    • = 0.9834−0.1539
    • = 0.8295
    Therefore, answer to all the questions using binomial distribution are shown below.
    Know more about Binomial distribution here:
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    The complete question is given below:
    Medical treatment will cure about  87% of all people who suffer from a certain eye disorder. Suppose a large medical clinic treats 57 people with this disorder. Let r be a random variable that represents the number of people that will recover. The clinic wants a probability distribution for r.
    A. Write a brief but complete description in which you explain why the normal approximation to the binomial would apply. Are the assumptions satisfied? Explain.
    b. Estimate P(r≤47).
    c. Estimate P(47≤r≤55).

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