Number of people who have heard it
by the end of the day:
January 1 . . . . . 2
January 2 . . . . . 4
January 3 . . . . . 8
January 4 . . . . . 16
January 5 . . . . . 32
January 6 . . . . . 64
January 7 . . . . . 128
January 8 . . . . . 256
.
.
.
February 1 . . . . . 4,294,967,296
February 2 . . . . . 8,589,934,592 <=== more than the Earth's
human population.
Pick two points
(2, 18) and (4,21)
(21-18)/(4-2) = 3/2
The slope is 3/2
16
.......................
3/(x+2) = 2/x
multiply both fractions by x(x+2) to cancel out the bottoms
so it becomes 3x = 2x+4
ow subtract 2X from both sides and you get
x = 4
so it took Juan 4 hours
it took Yumi 2 hours more so 4+2 = 6 hours
