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Let A and B be two independent events such that P( A )=0.7, P( B )=k, P(A B)=0.8 What is the value of k ?

Options

  1. A5 7
  2. B0
  3. C2 7
  4. D1 7

Correct answer

C. 2 7

Step-by-step solution

P( A )=0.7 P(A)=0.3P( B )=k P(B)=1-kP(A B)=0.8 For independent events P(A B)=P(A) P(B)P(A B)=P(A)+P(B)-P(A) P(B) 0.8=0.3+1-k-0.3(1-k) 0.5=1-k-0.3+0.3 k 0.5=0.7-0.7 k 0.7 k=0.2 k= 2 7

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