Question

7 a new virus has an r₀ of 4 for each day. if three people are initially infected, calculate the number of people infected after the third day. a 48 b 255 c 192 d 3

Explanation:

Step1: Identify the formula for virus - spread

The formula for the number of infected people $N$ after $n$ days with an initial number of infected people $N_0$ and a basic reproduction number $R_0$ is $N = N_0\times R_0^n$.

Step2: Substitute the given values

Here, $N_0 = 3$, $R_0=4$, and $n = 3$. So we calculate $N=3\times4^3$.

Step3: Calculate $4^3$

$4^3=4\times4\times4 = 64$.

Step4: Calculate the final number of infected people

$N = 3\times64=192$.

Answer:

C. 192