For continuous growth..... we have this
A = A0*e^(r*t)
Where A is the final number, A0 is the original number, e = 2.718...., r = hourly growth rate as a decimal, t = time in hours
So we have
2500 = 4 * e^(.584 t) divide both sides by 4
625 = e^(.584 t) take the natural log, Ln, of both sides
Ln 625 = Ln ^(.584 t) and by a log property, we can write
Ln 625 = .584t * Ln e [ Ln e = 1....so....we can ignore this ]
Ln 625 = .584 t divide both sides by .584
Ln 625 / .584 = t ≈11.02 hrs = 11 hrs