Solution: If it takes 1 minute to make a phone call, it takes 6 times to notify 50 people, that is, when one person knows, he will call the second person, and at this time * * * two people know (1 person notification 1 minute), and two people call each other separately, and at this time * * four people know (. * * * Eight people know (four people notice 1 minute) that eight people call each other separately, and at this time * * sixteen people know (eight people notice 1 minute) that sixteen people call each other separately, and at this time * * * thirty-two people know (16 people notice/kloc-0).
2. How long does it take to call up to fifty students in the primary school math book?
Solution: Suppose it takes 1 minute to make a phone call.
Then: it takes 6 times to notify 50 people, that is:
When one person knows, call the second person. At this time, * * * two people know (1 person notification 1 minute).
Two people call each other separately, and at this time * * * four people know (two people call 1 minute).
Four people call each other separately, and then * * * eight people know (four people call 1 minute).
Eight people call each other separately, and then * * * sixteen people know (eight people call 1 minute).
16 people call each other separately, and at this time * * * 32 people know (16 people call 1 minute).
At this time, there are still 18 people who don't know. Ask 18 people who know to notify again (18 people to notify 1 minute).
Because they are all carried out at the same time, it will take at least 6 minutes to inform everyone.