You can
put this solution on YOUR website!ignoring the first person for now, lets look at the end of the periods...
at end of first period = 3 new people told
at end of second period = 3x3 new people told
at end of third period = 3x3x3 new people told
at end of fourth period = 3x3x3x3
at end of fifth period = 3x3x3x3x3
at end of sixth period = 3x3x3x3x3x3
so a=3, ratio = 3, n = 6
Sn = a(r^n-1)/(r-1) so S=3(3^6-1)/(3-1)
S = 3x(729-1)/2
S=1092 plus the original person = 1093 people by the end of the day.