- #1
DanielJackins
- 40
- 0
Having a lot of trouble with this question.
So first I tried making an equation, and I wrote that the probability = P(rolling a 6)+P(rolling a 6 and not a 7 on the first roll and not a 9 on the first roll) + P(rolling a 6 and not a 7 on the first roll and not a 9 on the first roll and not a 7 on the second roll and not a 9 on the second roll) + ...
At this point I said let P(6) = x, P(not a 7) = y, P(not a 9) = z.
So I have P= x+xyz+xy^2z^2+... Factor out the x;
x(1+yz+y^2z^2+...)
Then I rewrote that as x*the sum of (y^i)(z^i) from i = 0 to infinity. Using an identity I got this to be x*[1/(1-yz)]. I subbed the numbers into that, and got .5357 as an answer. Now, I don't know what the correct answer is but that seems wrong to me.
Can anyone help?
Thanks
So first I tried making an equation, and I wrote that the probability = P(rolling a 6)+P(rolling a 6 and not a 7 on the first roll and not a 9 on the first roll) + P(rolling a 6 and not a 7 on the first roll and not a 9 on the first roll and not a 7 on the second roll and not a 9 on the second roll) + ...
At this point I said let P(6) = x, P(not a 7) = y, P(not a 9) = z.
So I have P= x+xyz+xy^2z^2+... Factor out the x;
x(1+yz+y^2z^2+...)
Then I rewrote that as x*the sum of (y^i)(z^i) from i = 0 to infinity. Using an identity I got this to be x*[1/(1-yz)]. I subbed the numbers into that, and got .5357 as an answer. Now, I don't know what the correct answer is but that seems wrong to me.
Can anyone help?
Thanks