GATE 2018 CS – Question 25
Two people, P and Q, decide to independently roll two identical dice, each with 6 faces, numbered 1 to 6. The person with the lower number wins. In case of a tie, they roll the dice repeatedly until there is no tie. Define a trial as a throw of the dice by P and Q. Assume that all 6 numbers on each dice are equi-probable and that all trials are independent. The probability (rounded to 3 decimal places) that one of them wins on the third trial is ________.
Practise this question in The GATE Grind →
Show answer and explanation
Correct answer: 0.01 to 0.03
Explanation
A trial is a tie with probability $\frac16$ and decisive with probability $\frac56$. Winning on the third trial needs two ties and then a decisive one: $\left(\frac16\right)^2\cdot\frac56=0.0231$.