You are interested in estimating the the mean lifespan of

Last updated: 7/25/2022

You are interested in estimating the the mean lifespan of a cell phone. From past data, you estimate that the standard deviation to be approximately 1.3 years. What sample size would you need to in order to estimate the mean lifespan of a cell phone, with a 90% confidence level, to within 0.5 years? Sample Size: n ≥