posted by linn on .
roll 2 standard dice and add the numbers. what is the probability of getting a number larger than 9 for the first time on the third roll?
If you make a table for all the combinations of rolling dice you will notice that there are 6/36 possible ways to roll a sum greater than a nine. You are going to roll the dice 3 times and you do not want the sum of greater than 9 on the first 2 rolls but you do want a sum great than 9 on the 3rd roll. Look at the favorable probability for each one and then multiply them together. So 1st roll probability not greater than 9 30/36. 2nd roll probability not greater than 9 30/36. 3rd roll probability greater than 9 6/36. Multiply 30/36 * 30/36 * 6/36.
A die is rolled once. The probability of obtaining an odd number is