Incorrect probability answer in strategy guide?

[sj34]

The question is: "what is the probability that the sum of two dice will yield 10 or lower"?

Shouldn't this be 1 - 4/36, rather than 1-3/36 as the answer key in the strategy guide implies? (Numbers Properties strategy guide, probabilities question number 1).

Four being (5,5), (6,6), (5,6) and (6,5)

Thanks

[sj34]

Actually please ignore this topic. Misread the question, asking for less than or equal to, not just less than.

[RonPurewal]

Actually please ignore this topic. Misread the question, asking for less than or equal to, not just less than.

yeah.

incidentally, that solution wouldn't be correct for "less than", either, because you forgot 4+6 and 6+4.
o_O

the best way to avoid these kinds of mistakes, by the way, is just to organize the outcomes of the dice throws into a 6 x 6 grid -- 1 through 6 on the rows, 1 through 6 on the columns, each cell represents a distinct outcome of the dice throw.
if you do this, you'll be much less likely to overlook outcomes (as you did here). i.e., this stuff happens from time to time, but it sure happens a lot less if you're organized.

--

incidentally, i don't think you'll see problems about actual dice on the gmat, because i think gambling is one of those "controversial" and therefore prohibited topics. (you'll notice also that there are never CR questions about religion, or divorce, or abortion, or illegal drugs, or xxxxxx or yyyyyy or zzzzzz.) so, you should be sure that you can generalize this kind of reasoning to similar topics.