Every hour virus increases by 16 times itself due to the antivirus/anti agent present, only half of them survive


Given that initial value = x
per hour, x increases by x * 16 * 1/2 = x * 8
After shows, there are 2^40 viruses because the virus multiplies itself, the growth is exponential so for 8 hours
$$x\cdot\left(8\right)^8=2^{40}$$
$$x\cdot\left(2^3\right)^8=2^{40}$$
$$x\cdot2^{24}=2^{40}$$
$$x=\frac{2^{40}}{2^{24}}$$
$$x=2^{40-24}$$
$$x=2^{16}$$


$$Answer\ =\ A$$

x = 2 ^ 16

A