In a newspaper ad, a car dealer lists a 2001 Chrysler, a 2010 Ford, and a 2008

Question:

In a newspaper ad, a car lists a 2001 Chrysler, a 2010 Ford, and a 2008 Buick. If the numbers of inquiries he will get about these cars may be regarded as independent random variables having Poisson distributions with the parameters λ1 = 3.6, λ2 = 5.8, and λ3 = 4.6, what are the probabilities that altogether he will receive
(a) Fewer than 10 inquiries about these cars;
(b) Anywhere from 15 to 20 inquiries about these cars;
(c) At least 18 inquiries about these cars?
Dealer
A dealer in the securities market is an individual or firm who stands ready and willing to buy a security for its own account (at its bid price) or sell from its own account (at its ask price). A dealer seeks to profit from the spread between the...