Don L. answered 03/18/15
Tutor
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Don - Math/Science Tutor from Elementary School to College level
if you roll the die twice, it will have total of 36 outcomes. where 6 choices on the first roll and 6 choices on the 2nd roll, which 6x6 = 36
for your question, there is 3 outcomes if you roll for a even number for the first time so, the probability will be 3/6 or 1/2.
for the second time roll, it will also be 3/6 or 1/2 for odd number.
due to the two outcomes are independent. the probability for both rolls will be
(1/2)*(1/2) = 1/4
Another way of seeing this.
below are the 36 possibilities. 9 of them is the one that satisfy your requirement. 9/36 = 1/4
(1,1)(1,2)(1,3)(1,4)(1,5)(1,6)
(2,1)(2,2)(2,3)(2,4)(2,5)(2,6)
(3,1)(3,2)(3,3)(3,4)(3,5)(3,6)
(4,1)(4,2)(4,3)(4,4)(4,5)(4,6)
(5,1)(5,2)(5,3)(5,4)(5,5)(5,6)
(6,1)(6,2)(6,3)(6,4)(6,5)(6,6)
(6,1)(6,2)(6,3)(6,4)(6,5)(6,6)