Answer
7,776 machines will be infected.
Formula
$N(n)=N_0× 5^n$
Work Step by Step
At the start, 1 computer is infected.
50 emails × 10% = 5 new infections per hour, per infected machine.
Hour 1: 1+ 5 = 6
Hour 2: 6 × 5 = 30, 30 + 6 = 36
Hour 3: 36 × 5 = 180, 180 + 36 = 216
Hour 4: 216 × 5 = 1080, 1080 + 216 = 1296
Hour 5: 1296 × 5 = 6480, 6480+ 1296 = 7776
If $N_0$ is the initial number of infected machines (which is 1), the general formula for the number of machines infected after $n$ hours is:
$N(n)=N_0× 5^n$
