Sheet # 49 Critical Thinking

Name: _____________________ Date_____________

One person makes 2 telephone calls to 2 people and tells them a secret. Then each of these people tells 2 other persons over the phone. Suppose this continues and each telephone call lasts 1 minute.

a) How long will it take for 250 people to know the secret?

b) If What if one person tells 3 people , they in turn tell 3 more people, and so on? How long will it take for 250 people to know the secret?

Answer for sheet # 49

a)

Round #
People Informed
Time spent (minutes)
1
2
2
2
2 x 2 = 4
2 (parallel phone calls)
3
4 x 2 = 8
2
4
16
2
5
32
2
6
64
2
7
128
2
8
256
2

It will take about 15 to 16 minutes to contact over 256 people

b)

I t will take about 12 to 13 minutes to reach 256 people.
Round #
People Informed
Time spent (minutes)
1
3
3
2
3 x 3= 9
3 (parallel phone calls)
3
27
3
4
81
3
5
243
3