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In an experiment, the probability that event AA occurs is 67\frac{6}{7}, the probability that event BB occurs is 38\frac{3}{8}, and the probability that event AA occurs given that event BB occurs is 67\frac{6}{7}. Are AA and BB independent events?

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Q. In an experiment, the probability that event AA occurs is 67\frac{6}{7}, the probability that event BB occurs is 38\frac{3}{8}, and the probability that event AA occurs given that event BB occurs is 67\frac{6}{7}. Are AA and BB independent events?
  1. Given Information: We are given:\newlineP(A)=67P(A) = \frac{6}{7}\newlineP(B)=38P(B) = \frac{3}{8}\newlineP(AB)=67P(A|B) = \frac{6}{7}\newlineIdentify the definition of independent events. Two events AA and BB are independent if the occurrence of one does not affect the probability of the occurrence of the other, which mathematically means P(AB)=P(A)P(A|B) = P(A).
  2. Definition of Independent Events: Since we are given P(AB)P(A|B), we can use the definition of conditional probability to find P(AB)P(A \cap B). The formula for conditional probability is P(AB)=P(AB)P(B)P(A|B) = \frac{P(A \cap B)}{P(B)}.
  3. Calculate P(AB)P(A \cap B): We can rearrange the formula to find P(AB)P(A \cap B):
    P(AB)=P(AB)×P(B)P(A \cap B) = P(A|B) \times P(B)
    Substitute the given probabilities into the equation:
    P(AB)=(67)×(38)P(A \cap B) = (\frac{6}{7}) \times (\frac{3}{8})
  4. Check for Independence: Perform the multiplication to find P(AB)P(A \cap B):P(AB)=67×38P(A \cap B) = \frac{6}{7} \times \frac{3}{8}P(AB)=1856P(A \cap B) = \frac{18}{56}P(AB)=928P(A \cap B) = \frac{9}{28}
  5. Check for Independence: Perform the multiplication to find P(AB)P(A \cap B):P(AB)=67×38P(A \cap B) = \frac{6}{7} \times \frac{3}{8}P(AB)=1856P(A \cap B) = \frac{18}{56}P(AB)=928P(A \cap B) = \frac{9}{28}Now, let's check if P(AB)P(A \cap B) is equal to P(A)×P(B)P(A) \times P(B) to determine if events A and B are independent.P(A)×P(B)=67×38P(A) \times P(B) = \frac{6}{7} \times \frac{3}{8}P(A)×P(B)=1856P(A) \times P(B) = \frac{18}{56}P(A)×P(B)=928P(A) \times P(B) = \frac{9}{28}
  6. Check for Independence: Perform the multiplication to find P(AB)P(A \cap B):P(AB)=67×38P(A \cap B) = \frac{6}{7} \times \frac{3}{8}P(AB)=1856P(A \cap B) = \frac{18}{56}P(AB)=928P(A \cap B) = \frac{9}{28}Now, let's check if P(AB)P(A \cap B) is equal to P(A)×P(B)P(A) \times P(B) to determine if events A and B are independent.P(A)×P(B)=67×38P(A) \times P(B) = \frac{6}{7} \times \frac{3}{8}P(A)×P(B)=1856P(A) \times P(B) = \frac{18}{56}P(A)×P(B)=928P(A) \times P(B) = \frac{9}{28}Since P(AB)=P(A)×P(B)P(A \cap B) = P(A) \times P(B), we conclude that events A and B are independent because the joint probability is equal to the product of the individual probabilities.

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