new exercise - stuck

I don't have any clue how to solve this exercise

The supplier knows that there is a 0.3 chance that customers will buy a certain product.
If the supplier only has 3 pieces of that product in stock, what is the probability that less than five customers will be needed to use all the stock.

tx in advance for tips


Less is more. Stay pure. Stay poor.
I am not great at these problems, but can it get converted into a marble and urn question?

?If you had an urn and a probability of 30% for selecting a blue marble. And the marbles are replaced back into the urn after each draw. What is the probability of selecting 3 blue marbles in five draws?

pbinom(3, 5, 0.3)
Now remember, that I am not good at these things!