GRE Quantitative Practice, Quantitative Comparison
Question 3
Quantity A The square root of 30 
Quantity B The greatest prime 

Explanatory Answer
First estimate Quantity A. Since 5^{2} = 25 and 6^{2} = 36, the square root of 30 must be a noninteger between 5 and 6. As for Quantity B, the greatest prime factor of 30 is 5. Therefore, Quantity A is greater than Quantity B. The correct response is (A).