Answer
$\frac{3}{5}$
Work Step by Step
We know that $probability=\frac{\text{number of favorable outcomes}}{\text{number of all outcomes}}$
The number of all outcomes is $10+15+20+5=50$, out of these $10+15+5=30$ correspond to the desirable selection.
Hence here the probability is $\frac{30}{50}=\frac{3}{5}$
