A clinical trial is run to assess the efficacy of a new pacemaker device in patients with atrial fibrillation (AF).Two hundred participants are randomized to receive the new pacemaker or a currently available pacemaker.There are two primary outcomes of interest - the number of days in a three-month period with an atrial fibrillation event and hospitalization for atrial fibrillation over the three month follow-up period.Data on baseline characteristics and the outcomes are shown below.

Baseline Characteristics

New Pacemaker (n=100)

Available Pacemaker (n=100)

Mean (SD) Age, years

67.3 (5.9)

66.9 (5.6)

% Male

48%

52%

Outcomes

Mean (SD) Number of days with AF event

8.4 (3.2)

14.9 (3.9)

% Hospitalized for AF

4%

9%

1. Compute a 95% confidence interval for the difference in mean number of days with an AF event between participants receiving the new pacemaker as compared to the available pacemaker.
2. Compute a 95% confidence interval for the mean number of days with an AF event among participants receiving the new pacemaker.