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AP EAMCET201921 Apr 2019Morning ShiftMathematicsProbabilityActual

A box contains 30 toys of same size in which 10 toys are white and all the remaining toys are blue. A toy is drawn at random from the box and it is replaced in the box after noting down its colour. If 5 toys are drawn in this way, then the probability of getting atmost 2 white toys is

Options

  1. A( 6 9 )^2
  2. B( 8 9 )^2
  3. C( 7 9 )^2
  4. D( 2 3 )^5

Correct answer

B. ( 8 9 )^2

Step-by-step solution

Required probability = No white ball + one white ball + two white ball aligned & = ( 2 3 )^5+ ^5 C₁ ( 2 3 )^4 ( 1 3 )^1+ ^5 C₂ ( 2 3 )^3 ( 1 3 )^2 & = ( 1 3 )^5 [2^5+5 2^4+10 2^3 ] & = ( 1 3 )^5[32+80+80]= 192 3^5 = 64 3 3^5 & = 64 3^4 = 8 8 3^2 3^2 = ( 8 9 )^2 aligned

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