In: Statistics and Probability
Suppose that 55% of all adults regularly consume coffee, 45% regularly consume car- bonated soda, and 70% regularly consume at least one of these two products.
(a) What is the probability that a randomly selected adult regularly consumes both coffee and soda?
(b) What is the probability that a randomly selected adult doesn't regularly consume at least one of these two products?
solution
We have P(coffee )=0.55 and P( soda)=0.45
P( coffee or soda)=0.7
(a) What is the probability that a randomly selected adult regularly consumes both coffee and soda?
=>P(coffee and soda)= P(C\( \cap \)B)=P(C)+P(S)-P(C\( \cup \)S)
= 0.55+0.45-0.7
=0.3
(b) What is the probability that a randomly selected adult doesn't regularly consume at least one of these two products?
=>P(\( \overline {C\cup S} \))=1-P(C\( \cup \)S)=1-0.7=0.3
Answer
(a).P(coffee and soda) is P(C\( \cap \)S)=0.3
(b). P(coffee or soda) is P(\( \overline {C\cup S} \))=0.3