Answer
$\frac{10}{1001}$
Work Step by Step
We know that $probability=\frac{\text{number of favourable outcomes}}{\text{number of all outcomes}}$
The number of all outcomes is ${15\choose6}=5005$, the number of favourable outcomes is $50$, thus probability: $\frac{50}{5005}=\frac{10}{1001}$
