9) A survey of 865 voters in one state reveals that 408 favor approval of an issue before the legislature. Construct a 95% confidence interval for the proportion of all voters in the state who favor approval. 10) The drying times for a certain type of cement are normally distributed with a standard deviation of 73 minutes. A researcher wishes to estimate the mean drying time for this type of cement. Find the sample size needed to assure with 68% confidence that the sample mean will not differ from the population mean by more than 4 minutes