Answer:
(a) The expected number of guests until the next one pays by American Express credit card is 4.
(b) The probability that the first guest to use an American Express is within the first 10 to checkout is 0.0215.
Step-by-step explanation:
The random variable <em>X</em> can be defined as the number of guests until the next one pays by American Express credit card
The probability that a guest paying by American Express credit card is, <em>p</em> = 0.20.
The random variable <em>X</em> follows a Geometric distribution since it is defined as the number of trials before the first success.
The probability mass function of <em>X</em> is:
(a)
The expected value of a Geometric distribution is:
Compute the expected number of guests until the next one pays by American Express credit card as follows:
Thus, the expected number of guests until the next one pays by American Express credit card is 4.
(b)
Compute the probability that the first guest to use an American Express is within the first 10 to checkout as follows:
Thus, the probability that the first guest to use an American Express is within the first 10 to checkout is 0.0215.