10. Minting Quarters Quarters are currently minted with weights having a mean of 5.670 g and a standard deviation of 0.062 g. New equipment is being tested in an attempt to improve quality by reducing variation. A simple random sample of 24 quarters is x2 x R 5 228.9638.d 2 L 5 152.8222 x 5 2700 s 2 75, a 5 0.01, n 5 51, s 5 70.

s , 15, a 5 0.01, n 5 21, s 5 10.

s . 15, a 5 0.05, n 5 5, s 5 30.

s 2 2.00, a 5 0.05, n 5 10, s 5 3.00.

s 5 !35>12 < 1.7.

442 Chapter 8 Hypothesis Testing obtained from those manufactured with the new equipment, and this sample has a standard deviation of 0.049 g. Use a 0.05 significance level to test the claim that quarters manufactured with the new equipment have weights with a standard deviation less than 0.062 g. Does the new equipment appear to be effective in reducing the variation of weights? What would be an adverse consequence of having quarters with weights that vary too much?