Question

Suppose you do an experiment where you roll a standard die twice. You decide to keep performing this experiment unless you get a sum of the rolls to be exactly 6. How many times do you feel you have to do this experiment on an average?

Answer 1

7.2 times

Explanation:

There are 36 possible outcomes when rolling a die twice and adding the results. The outcomes for which the sum is 6 are:

Sum = 6: {1,5; 2,4; 3,3; 4,2; 5,1}

Therefore there is a 5 in 36 chance that the sum will be 6.

The expected number of trials to achieve that result is given by:

`E = (36)/(5)\\E=7.2\ times`

On average, it would take 7.2 trials to achieve a sum of 6.