Math Post #4: Telephone tree

A telephone tree is used to send messages. The person at the top calls 2 people. Each person calls 2 more people. Suppose it takes 1 min to call someone. A message is relayed until the bottom row of the tree has 256 people. How long did this take? How do you know?

It takes 16 minutes to call 256 people. So, one person calls 2 people which took him/her 2 minutes, 1 minute for each call. So, now those two people call two more people each, which took them 2 more minutes. All this goes on till the have called 256 people.

1+1=2

2+2=4

4+4=8

8+8=16

16+16=32

32+32=64

64+64=128

128+128=256

So, if everyone calls two more people when they were called. Altogether it would take them 16 minutes.

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3 comments

  1. Hi Areeba,
    I really liked your post, it was short and easy to follow. I found it quite helpful. In my math post, I answered the question in a way quite similar to you, nice work.
    Yours faithfully,
    Eeman

    Like

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