Hi
Note: The probability of x successes in n trials is:
P = nCx*where p and q are the probabilities of success and failure respectively.
In this case p = .5 and q = .5
nCx =
Assume sales calls are independent and the employee is doing 2 sales calls
P(at least one of the two sales calls is successful) = 1-P(none)= 1 - (.5)^2
P(at least one of the two sales calls is successful) = .75