Probability · JEE Main previous year questions

2009 2 questions

1. Q162009 · 27 Apr 2009 · Shift 1

   One ticket is selected at random from 50 tickets numbered $00,01,02,\dots ,49$. Then the probability that the sum of the digits on the selected ticket is 8, given that the product of these digits is zero, equals :

   1. A.$\frac{1}{7}$
   2. B.$\frac{5}{14}$
   3. C.$\frac{1}{50}$
   4. D.$\frac{1}{14}$
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   Answer: D

2. Q272009 · 27 Apr 2009 · Shift 1

   In a binomial distribution $B\left(n,p=\frac{1}{4}\right)$, if the probability of at least one success is greater than or equal to $\frac{9}{10}$, then $n$ is greater than :

   1. A.$\frac{1}{{\log }_{10}^4+{\log }_{10}^3}$
   2. B.$\frac{9}{{\log }_{10}^4-{\log }_{10}^3}$
   3. C.$\frac{4}{{\log }_{10}^4-{\log }_{10}^3}$
   4. D.$\frac{1}{{\log }_{10}^4-{\log }_{10}^3}$
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   Answer: D