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AP EAMCET201923 Apr 2019Morning ShiftMathematicsProbabilityActual

From a group of 50 students, two sections comprising of 20 and 30 students are formed. If Ram and Rahim are two particular students among the 50 students, then the probability that they both belong to the same section is

Options

  1. A( 25 49 )
  2. B( 12 23 )
  3. C( 13 23 )
  4. D( 24 49 )

Correct answer

A. ( 25 49 )

Step-by-step solution

Total number of students (=50 ) Number of ways of making groups if both the students are in first group (= 48 18 30 30 = 48 18 ) and number of ways of making groups if both the students are in second group (= 48 28 20 20 = 48 28 ) and total number of ways (= 50 20 30 30 = 50 20 ) ( gathered Required probability = 48 18 + 48 28 50 20 = 48 ! 18 ! 30 ! + 48 ! 28 ! 20 ! 50 ! 20 ! 30 ! = 1 30 29 + 1 20 19 50 49 20 19 30 29 = (20 19)+(30 29) (50 49) = 38+87 5 49 = 125 5 49 = 25 49 gathered ) Hence, option (a) is correct.

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