Question 15
Let $P(x) = x^2 - 3x - 9.$ A real number $x$ is chosen at random from the interval $5 \le x \le 15.$ The probability that $\left\lfloor \sqrt{P(x)} \right\rfloor = \sqrt{P(\lfloor x \rfloor)}$ is equal to $\frac{\sqrt{a} + \sqrt{b} + \sqrt{c} - d}{e},$ where $a,$ $b,$ $c,$ $d,$ and $e$ are positive integers. Find $a + b + c + d + e.$