You are a researcher studying the lifespan of a certain species of bacteria. A preliminary sample of 30 bacteria reveals a sample mean of a = 78 hours with a standard deviation of s - 4.8 hours. You would like to estimate the mean lifespan for this species of bacteria to within a margin of error of 0.5 hours at a 95% level of confidence. What sample size should you gather to achieve a 0.5 hour margin of error? Round your answer up to the nearest whole number. n = bacteria