Question

A student wants to conduct an experiment to see how quickly information can travel. On Day 1 of the experiment, the student tells three friends a personal fact. On Day 2, those three friends share the fact with three new people each. Assuming this pattern continues, how many people will hear the fact on Day 7 of the experiment?

Answer 1

3 people know a fact in 1st day.
In 2nd day they share it with 3 people each=3×3
Now 3×3 people shares it with 3 people each. and so on...
So,
3+3²+3³+3⁴+3^5+3^6+3^7
=3279 no of people altogether , will hear from 1st day to 7th day...
On the day 7,no of people who will hear the fact=3^7=2187