So I’m reading a book and this problem is given:
What are the odds against rolling a one or a two when rolling a die?
Now the answer Ive come up with is 2:1. But why is the ratio as a percentage 33%?
Doesn’t 4/6=2/3=66%?
Am I missing something?
It’s 66% (well, 67% if you’re rounding it), if that’s exactly how the question was phrased (and the die is six-sided).
If the die was three-sided, it would be 33%, but it is kinda hard to imagine such a die.
I think either you (hberi) or the book’s author are confusing odds against with odds of.
Indeed. Where does the 33% figure come from?
I came up with 33% because 2:1 as a fraction you put 1 as the numerator and add 2+1 to get the denominator which is 1/3. So this is where I’m confused? Am I not turning my ratio into a fraction correctly?
The sad part is that I understand how they come up with 2:1 but I cant get it to a percentage that makes sense?
Wow. Just got it. Woooooo that was going to kill me. I got all caught up on the wording of the favorite vs underdog. http://m.pinterest.com/pin/200339883394174796/
I think a sort of inflated, round-ended triangular prism would do it. The number rolled is the one you can’t see - or the numbers could be printed on little saddle - like cutouts on the long edges
Or here’s another design.
I thought everyone knew that a d3 was just a d6/2 rounded up. 
Well, get one of those triangular rulers and write the following numbers on the three sides, using a label-maker:
-2, -1, 1
Flip the ruler through the air, let it land. Your “roll” is the difference between the two visible sides, i.e.:
-2, -1: 1
-1, 1: 2
1, -2: 3
Isn’t the easiest thing just to make a cube with two sides numbered 1, etc. Or just roll a regular die and subtract 2 if the number exceeds 3.