In a survey conducted by a polling company, 1100 adult americans were asked how many hours they worked in the previous week. based on the results, a 95% confidence interval for the mean number of hours worked had a lower bound of 42.7 and an upper bound of 44.5. provide two recommendations for decreasing the margin of error of the interval. select all that apply. a. decrease the sample size. b. increase the confidence level. c. increase the sample size. d. decrease the confidence level. e. decrease the standard deviation of hours worked. f. use fewer degrees of freedom.