Q29 / 108 · NTA Abhyas (JEE Main) 2020 · Mathematics · Probability

Dice A has 4 red and 2 white faces whereas dice B has 3 red and 3 white faces. A coin is tossed once, if it falls head then the game continues by throwing the dice A and if it falls tail then the dice B is to be used. If red turns up at first 3 throws, then the probability that dice A is being used is

  • A
    737
  • Correct answer
    B
    6491
  • C
    941
  • D
    2735

Solution

R→ Red turns up at first three throws
A→ Dice A is selected. PA=12
B→ Dice B is selected. PB=12
Using Bayes theorem, we get,
PAR=PA∩RPR=PA×PRAPA×PRA+PBPRB
=12×23312×233+12123=6491

Hence, the correct answer is option: 'B'.

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