DMACC Stats WS 9.2

1. Researchers conducted a study to see if magnet therapy was effective in

treating back pain (Worldwide, $5 billion dollars a year is spent on magnet

therapy). They divided the groups into a control group and a placebo

group. Here are the results. (Pain level is measured 0 to 1, 0 is no pain)

Pain level after magnet: n₁ = 20, 1.49, $1 = .96

Pain Level after placebo: n₂ = 20, 2.44, 82 = 1.4

Construct a 95% Confidence Interval for μ₁ −μ2

2. Coke vs. Pepsi! Samples of 12 oz. cans of Pepsi and Coke were examined to

see how much soda each can contained.

Coke: n₁ = 36, *₁ = 12.19 oz, $₁ = .11oz

Pepsi: n2 = 20, x2 12.29 oz, s2 = .96 oz

Construct a 98% Confidence Interval for ₁-442