Let $PQ$ be a diameter of a circle and let $R$ be a point on the segment $PQ$ such that $PR:RQ=6:7$. Let $S$ be a point on the circle such that $SR$ is perpendicular to $PQ$. Let $ST$ be the diameter through $S$. If $[XYZ]$ denotes the area of the triangle $XYZ$, find $\frac {[PQS]}{[RST]}$ to the nearest integer.