You are doing a study on sleep deprivation. you take a sample of n = 25 individuals and deprive of them sleep so that they only get 4 hours of sleep for two nights. you then have them each solve a puzzle, and find that the mean time to solve the puzzle is m = 30 minutes. you know that for the population, the mean time to solve the puzzle is μ = 10 minutes and the standard deviation is σ = 20. you want to answer the following research question: does sleep deprivation have an effect on the amount of time it takes to solve this puzzle? what is the standard error of the sample mean