A student secures 90%, 60% and 54% marks in test papers with 100, 150 and 200 respectively as maximum marks. The percentage of his aggregate is:

$$\begin{gathered} total score=(90\% of 100+60\% of 150+54\% of 200) \\ =90+90+108 \\ =288 \\ total maximum marks=100+150+200 \\ =450 \\ Aggregate percentage=(\frac{288}{450}\times 100)\% \\ =64\% \end{gathered}$$