The formula H=1/r (ln P- ln A) models the number of hours it takes a bacteria culture to decline, where H is the number of hours, r is the rate of decline, P is the initial bacteria population, and A is the reduced bacteria population. A laboratory assistant tests an antibiotic that causes a rate of decline of 0.14 . How long should it take for a population of 8000 bacteria to shrink to 500?