2. Solved Papers
  3. JEE Main & Advanced

JEE Main & Advanced JEE Main Paper (Held on 08-4-2019 Afternoon)

  • question_answer
    The minimum number of times one has to  toss a fair coin so that the probability of observing at least one head is at least 90% is: [JEE Main 8-4-2019 Afternoon]

    A) 5                                 

    B) 3

    C) 2                     

    D) 4

    Correct Answer: D

    Solution :

    Probability of observing at least one head out of n tosses \[=1-{{\left( \frac{1}{2} \right)}^{n}}\ge 0.9\]\[\Rightarrow \]\[{{\left( \frac{1}{2} \right)}^{n}}\le 0.1\]\[\Rightarrow \]\[n\ge 4\] \[\Rightarrow \]minimum number of tosses = 4


You need to login to perform this action.
You will be redirected in 3 sec spinner