## Chemistry: The Central Science (13th Edition)

The signals are transmitted in the form of electromagnetic radiation, which travels in vacuum at speed of light $c\approx2.998\times10^8m/s$ We know that $1mi\approx1609.344m$ So, $c\approx1.863\times10^5mi/s$ Therefore, the time it takes for the transmitted signals to travel from the spacecraft to the Earth is $$t=\frac{3.91\times10^8mi}{1.863\times10^5mi/s}$$$$t\approx2.099\times10^3s\approx2099s\approx35minutes$$