Sure, I can help you create a simulation to estimate the probability of a friend receiving a musical greeting card.
Here's a simple Python code that simulates the process:
```python
import random
num_friends = 1000 # the number of friends
num_musical_cards = 0 # the number of friends who received musical cards
# simulate the card distribution for each friend
for friend in range(num_friends):
if random.random() < 0.3:
num_musical_cards += 1
# calculate the probability of a friend receiving a musical card
prob = num_musical_cards / num_friends
print("Probability of a friend receiving a musical card:", prob)
```
In this simulation, we create a loop that simulates the card distribution for each friend. We randomly assign a musical card to each friend with a 30% chance. Then, we calculate the probability of a friend receiving a musical card by dividing the number of friends who received musical cards by the total number of friends.
You can adjust the `num_friends` and `random.random() < 0.3` parameters to match your specific scenario.