List of top Quantitative Aptitude Questions on Surds and Indices asked in CAT

A man invests Rs. 5000 at 6% simple interest per annum. How much interest will he earn in 3 years? 
 

A boat travels 24 km upstream in 6 hours and 30 km downstream in 5 hours. What is the speed of the boat in still water? 
 

Which among $2^{1/2}$, $3^{1/3}$, $4^{1/4}$, $6^{1/6}$, and $12^{1/12}$ is the largest?