Is r/s^2 a terminating decimal?
1) s = 225
2) r = 81
A decimal is terminating only if the denominator has prime factorization of 5 and/or 2.
Stat 1: s = 225, means that the denominator includes 3 as a prime factor. Since this says nothing about the numerator we don't know if the 3's get canceled out. Insuff.
Stat 2: Says nothing about the denominator. Insuff.
Together: Tells us that the fraction is 81/225 * 225. We can answer the question. (yes) Suff.