#### Answer

SAT's z-score is higher, therefore it is relatively better.

#### Work Step by Step

The z-scores: SAT: $z_{SAT}=\frac{value-mean}{standard \ deviation}=\frac{1490-1518}{325}=-0.086$.
ACT: $z_{ACT}=\frac{value-mean}{standard \ deviation}=\frac{17-21.1}{4.8}=-0.854$. The SAT's z-score is higher, therefore it is relatively better.