In order to revitalize the tourism industry, Sichuan Province issued a total of 20 million panda discount cards to the domestic market in 2009. Panda gold cards are distributed to people outside the province, and panda silver cards are distributed to people in the province. A travel company organized a tour group of 36 tourists to visit places of interest in Sichuan, including tourists from outside the province, and the rest were tourists from within the province. Some tourists from outside the province hold gold cards, while others come from inside the province.
(1) Immediately interview two tourists in the group to find out the probability that just 1 person holds the silver card;
(2) Interview two tourists randomly in the group to find out the probability that the number of gold card holders is equal to that of silver card holders.
18) This topic mainly examines the probability calculation of independent events and mutually exclusive events, and examines the ability to apply probability knowledge to practical problems.
According to the meaning of the question, there are 27 tourists from outside the province, 9 of whom hold gold cards; There are 9 tourists in the province, 6 of whom hold silver cards.
Let event A be "Interview 2 group members, and just 1 member holds a silver card.
Therefore, the probability that 1 of 2 people in the interview group holds a bank card is
(2) Let event B be "two people are interviewed in a group, and the number of gold cards is equal to that of silver cards".
The event is "Of the two people interviewed by the group, 0 holds a gold card and 0 holds a silver card".
The incident was "Of the two people interviewed by the group, 1 holds a gold card and 1 holds a silver card".
I did something wrong ~ ~ and cried to death.
For the flow of each line segment, establish a limiting formula, such as:
S _ a & lt= 26
S _ b & lt= 12