Question 1960
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.