A certain die is weighted such that probabilities of showing a 1, 2, 3, 4, 5, and 6 are
A) If two such dice are thrown, and you are told that the sum of the two is 10 or larger. What is the probability that the result was a pair of 5's?
B) How many times would you have to throw this die to have the probability of throwing a 2 exceed 40 percent?
The Attempt at a Solution
A) For this the possible outcomes for a sum of 10 or greater are:
Getting rid of duplicates, since order doesn't matter there is a 1/4 chance it's double fives. I multiplied this by (8/34)(8/34) and got a probability of .01384
B) For this I used the equation
Probability = Successful outcomes/Total number of outcomes
so .4 = (8/34)/n
solving for n I get .588, which doesn't make sense.
I'm just learning statistics, so if anything I tried to do offends you mathematically, I'm very sorry!