Bunuel
Ann and Bob each randomly select an integer from the integers x to y, inclusive. What is the probability that the integer Ann selects is greater than the one Bob selects?
(1) y - x = 9
(2) y = -20
From statement 1 it is clear that two numbers have a difference of 9 which means we can have any number (for Ann and Bob we can select from these 10 umbers) which can be like
10,1 or 100,110 .... similallry so we can have 100 such arrangements for Ann and Bob and we have to find how many of them is such that Ann has more than Bob.
So in 100 numbers we can have only 45 ways so one number is greater than other (excluding situations when both are same) so 45/100 is the probability. which makes A sufficient.
Now, 2 cannot be solution since if y is a fixed value, their can be inffinite numbers x which is greater so we cannot find probbaility