Recall that to find the theoretical probability we use the following expression:
![\frac{\text{favorable cases}}{total\text{ cases}}.](https://img.qammunity.org/2023/formulas/mathematics/college/5tlqmvaw7n28s9mtu41wbtw3rvkp1ne0op.png)
Since the jar contains 20 yellow marbles, 55 green marbles, and 25 purple marbles, then the jar contains 20+55+25=100 marbles. Therefore, the theoretical probability of picking a green or a yellow marble is:
![(20+55)/(100)=(75)/(100)=0.75.](https://img.qammunity.org/2023/formulas/mathematics/high-school/i2y2g4uykxp9suogt2l5snpba41yfptlzt.png)
The above decimal number written as a percentage is 75%.
Answer: Option D.