Solution:
Given that

The probability of an event is expressed as

In this case, the total number of possible outcome equals 125.
Step 1: Evaluate the probability of picking a red block.
Thus,

Step 2: Evaluate the probability of picking a purple block.
Thus,

Step 3: Evaluate the probability of picking a red or purple block.
The probability of picking a red or purple block is expressed as

Thus, we have

Hence, we have the theoretical probability P(red or purple) to be
