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Assuming the probability of a single sample testing positive is 0.15​, find the probability of a positive result for two samples combined into one mixture. Is the probability low enough so that further testing of the individual samples is rarely​ necessary?

1 Answer

5 votes

Answer:


P(Positive\ Mixture) = 0.2775

The probability is not low

Explanation:

Given


P(Single\ Positive) = 0.15


n = 2

Required


P(Positive\ Mixture)

First, we calculate the probability of single negative using the complement rule


P(Single\ Negative) = 1 - P(Single\ Positive)


P(Single\ Negative) = 1 - 0.15


P(Single\ Negative) = 0.85


P(Positive\ Mixture) is calculated using:


P(Positive\ Mixture) = 1 - P(All\ Negative) ---- i.e. complement rule

So, we have:


P(Positive\ Mixture) = 1 - 0.85^2


P(Positive\ Mixture) = 1 - 0.7225


P(Positive\ Mixture) = 0.2775

Probabilities less than 0.05 are considered low.

So, we can consider that the probability is not low because 0.2775 > 0.05

User Smrutiranjan Sahu
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