A study was conducted to see if the herbal supplement helped to descrese weight. After 12 weeks, 42 subjects using the herbal supplement and high-fiber, low-calorie diet had mean weight loss of 3.2 kg. And standard deviation of 3.3 kg. Throughout the same period, 42 subjects using the placebo and high-fiber, low-calorie diet had mean weight loss of 4.1 kg. And standard deviation of 3.9 kg.
Develop a 95% C. I. for mean differences.