You are a researcher studying the lifespan of a certain species of bacteria. A preliminary sample of 35 bacteria reveals a sample mean of
¯
x
=
80
hours with a standard deviation of
s
=
5.4
hours. You would like to estimate the mean lifespan for this species of bacteria to within a margin of error of 0.65 hours at a 90% level of confidence.
What sample size should you gather to achieve a 0.65 hour margin of error? Round your answer up to the nearest whole number