troublemaker676
Junior Member
- Joined
- Sep 1, 2005
- Messages
- 84
Have a question about a tricky word problem,
At 5:00 am 1 person called two other people to tell them about a huge secret, completeting these calls took 5 minutes. These people called two other people. (Those calls took place at 5:05.) Those people continued the chain by calling two people each. Assuming no one was called twice and that each set of calls occurred exactly 5 minutes after the previous calls, how amny people were aware of the secret at 6:00 am?
Now I set up a table,
....................0.........1.........2..........3..........4..........................12
Time..........5:00......5:05.....5:10......5:15....5:20.......................6:00
# of people...3............7.........15.........31.......63.........................?
who know
Then i found the differences
Diff.....................4...........8...........16.........32
Diff.............................4...........8...........16
Diff.....................................2..........2
Now i know when the second differences are all the same you know they will fit into a quadratic model, which means you factor out the # of people numbers into 2 factors each, then you find the equation. I'm not sure how to find the equation if the third differences are all the same. Can someone show me the process from where i left off?
At 5:00 am 1 person called two other people to tell them about a huge secret, completeting these calls took 5 minutes. These people called two other people. (Those calls took place at 5:05.) Those people continued the chain by calling two people each. Assuming no one was called twice and that each set of calls occurred exactly 5 minutes after the previous calls, how amny people were aware of the secret at 6:00 am?
Now I set up a table,
....................0.........1.........2..........3..........4..........................12
Time..........5:00......5:05.....5:10......5:15....5:20.......................6:00
# of people...3............7.........15.........31.......63.........................?
who know
Then i found the differences
Diff.....................4...........8...........16.........32
Diff.............................4...........8...........16
Diff.....................................2..........2
Now i know when the second differences are all the same you know they will fit into a quadratic model, which means you factor out the # of people numbers into 2 factors each, then you find the equation. I'm not sure how to find the equation if the third differences are all the same. Can someone show me the process from where i left off?