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Corrupted by their power, the judges running the popular game show America’s Next Top Mathematician have been taking bribes from many of the contestants. During each of two episodes, a given contestant is either allowed to stay on the show or is kicked off. If the contestant has been bribing the judges, she will be allowed to stay with probability 1. If the contestant has not been bribing the judges, she will be allowed to stay with probability 1/3, independent of what happens in earlier episodes. Suppose that 1/4 of the contestants have been bribing the judges. The same contestants bribe the judges in both rounds. (a) If you pick a random contestant who was allowed to stay during the first episode, what is the probability that she was bribing the judges? (b) If you pick a random contestant, what is the probability that she is allowed to stay during both episodes? (c) If you pick a random contestant who was allowed to stay during the first episode, what is the probability that she ge

User Kherel
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Answer:

(a) The probability that a contestant allowed to stay in the first episode is 0.5

(b) The probability that a contestant will be allowed to stay during both is 0.25

Explanation:

The given parameters are;

The probability that a contestant who has been bribing the judges will be allowed to stay = 1

The probability that a contestant who has mot been bribing the judges will be allowed to stay = 1/3

The proportion of the contestant that has been bribing the judges = 1/4

The contestant who bribe the judges in the first round = The contestants who bribe the judges in the second round

(a) Let the total number of contestants = x

Therefore;

The number of contestants in the second round = x/4 + 1/3×(x - x/4) = x/2

Which gives that, half of the contestants make it to the second round

The probability that a contestant allowed to stay in the first episode, Pₐ₁, is given as follows;

Probability = (The number of required outcome)/(The number of possible outcome)

∴ Pₐ₁ = (x/4)/(x/2) = 2/4 = 1/2 = 0.5

The probability that a contestant allowed to stay in the first episode = 0.5

(b) The probability that a contestant will be allowed to stay during both episode, Pₐ₁₂ is given as follows;

The number of contestant that will be allowed to stay after each episode = 1/2×(The number contestant in the previous episode)

Therefore;

The number of contestant that will be allowed to stay after the first episode = 1/2 × x = x/2

The number of contestant that will be allowed to stay after the second episode = 1/2 × x/2 = x/4

Therefore, the number of contestant that will be allowed to stay after both episode = x/4

Pₐ₁₂ = (The number of contestant that will be allowed to stay after both episode)/(The total number of contestants)

∴ Pₐ₁₂ = (x/4)/x = 1/4 = 0.25

The probability that a contestant will be allowed to stay during both = 0.25.

User Armondo
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