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MHT CET202415 May 2024Morning ShiftMathematicsProbabilityActual

A multiple choice examination has 5 questions. Each question has three alternative answers of which exactly one is correct. The probability that a student will get 4 or more correct answers just by guessing is

Options

  1. A17 243
  2. B13 243
  3. C11 243
  4. D10 243

Correct answer

C. 11 243

Step-by-step solution

Probability of getting correct answer (p)= 1 3 q=1- 1 3 = 2 3 Also, n =5 Required probability aligned & = P ( X 4) & = P ( X =4)+ P ( X =5) & = ^5 C ₄ ( 1 3 )^4 ( 2 3 )^1+ ^5 C ₅ ( 1 3 )^5 ( 2 3 )^0 & =5 ( 1 3 )^4 ( 2 3 )+1 ( 1 3 )^5 & = ( 1 3 )^4 ( 10 3 + 1 3 )= 11 3^5 = 11 243 aligned

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