What sample size would you need to estimate the average amount of time spent on non-school related assignments, within 2 minutes if you wanted to be 97% confident in your estimate, given σ=9.5.
Q. What sample size would you need to estimate the average amount of time spent on non-school related assignments, within 2 minutes if you wanted to be 97% confident in your estimate, given σ=9.5.
Identify Formula: Identify the formula to calculate the sample size for estimating a population mean with a certain level of confidence. The formula is:n=(Z⋅σ/E)2where n is the sample size, Z is the z-score corresponding to the desired confidence level, σ is the population standard deviation, and E is the margin of error (the maximum allowable error in the estimate).
Determine Z-Score: Determine the z-score corresponding to a 97% confidence level. This can be found using a z-table or a statistical calculator. For a 97% confidence level, the z-score is approximately 2.17.
Plug Known Values: Plug the known values into the formula. We have σ=9.5 (the standard deviation) and E=2 (the desired margin of error). Now we can substitute these values into the formula:n=(2.17×9.5/2)2
Perform Calculations: Perform the calculations step by step.First, calculate the numerator of the fraction:2.17×9.5=20.615Next, divide by the margin of error, E:20.615/2=10.3075Finally, square the result to find n:10.30752=106.2445625
Round Sample Size: Since the sample size must be a whole number, and you cannot have a fraction of a sample, round up to the nearest whole number. This ensures that the sample size is not smaller than needed for the desired confidence level.n=107 (rounded up from 106.2445625)