Q12 / 108 · NTA Abhyas (JEE Main) 2020 · Mathematics · Probability

The probability of a problem being solved by 3 students independently are 12, 13 and α respectively. If the probability that the problem is solved is PS, then PS lies in the interval (where, α∈0,1)

  • A
    0,12
  • B
    13,12
  • Correct answer
    C
    23,1
  • D
    13,23

Solution

Let 3 students are A,B,C and their probability of solving problems is PA,PB,PC respectively.
PA=12,PB=13,PC=α
Probability of the problem is being solved, 
PS=1-P(AC∩BC∩CC)
=1-PACPBCP(CC)
=1-1-PA1-PB1-PC
=1-12231-α
=23+13α

Hence, PS∈23,1

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

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