I don't know how to do this

10. A company has five warehouses, only two of which have a particular product in stock. A salesperson calls the five warehouses in a random order until a warehouse with the product is reached. Let X be the number of calls made by the salesperson. The probability distribution of X is given in the following table: *= # calls Number of calls by salesperson (X) 1 2 3 4 Probability 0.4 0.3 0.2 ? X = 5