(2) According to the data in the figure, we can know that there are 3 people who spend 6-8 hours online and 2 people who spend 8- 10 hours online. It is possible to randomly select two students from five students who have been online for 6- 10 hours, and at least 1 person has been online for 8-6500 hours.
analyse
( 1) a=50-6-25-3-2= 14，
The value of ∴a is14;
(2)∵ According to the data in the figure, there are 3 people who spend 6 ~ 8 hours online and 2 people who spend 8 ~ 10 hours online.
Draw a tree:
Manfen5.com manfen net
∴ There are 20 possibilities, and two students are randomly selected from five students who have been online for 6 ~ 10 hours.
Among them, there are at least 1 person who is online for 8 ~ 10 hours, and there are 14 possibilities.
(at least 1 person's online time is 8 ~ 10 hour) =14÷ 20 = manfen5.com.