A research group wishes to estimate the mean number of hours that high school students spend watching TV on a weekday. A margin of error of E=0.35 hour is desired. Past studies suggest that a...

A research group wishes to estimate the mean number of hours that high school students spend watching TV on a weekday. A margin of error of E=0.35 hour is desired. Past studies suggest that a population standard deviation of σ=1.2 hours is reasonable. Estimate the minimum sample size required to estimate the population mean with​ 95% confidence.

the required sample size is ?