x, y, and z are consecutive integers, and x < y < z. What is the average of x, y, and z?
(1) x = 11
(2) The average of y and z is 12.5.
[spoiler]Can we considered prime numbers as an option of consecutive integers? Also, how can stmt2 be sufficient?
OA is D[/spoiler]
Stat 1: X=11 this is enough to determine Y=12 and Z=13. You can compute the average after knowing all the values. Suff.
Stat 2: Y and Z has an average of 12.5 and they have to be consecutive numbers. There are no other choices other than Y being 12 and Z being 13, since Y<Z. Any other combination of Y,Z yielding average of 12.5 would not be consecutive integers. (e.g. Y=11, Z=14). With that in mind, X must be 11 and hence sufficient.