Statistics for Business: Decision Making and Analysis, 3rd Edition

Think About It

1. 21.

   1. Decreased because it becomes more difficult to halt the procedure.

   2. P(Type I) = .05²

2. 23.

   1. Under control unless there's a special sale or weekend shopping surge.

   2. Under control unless some problem causes a surge in calls.

   3. Out of control with surges during holiday season.

   4. Out of control with upward (or perhaps downward!) trend.

3. 25.

   1. Poisson, with λ = 4. Verify that counts in disjoint time intervals are independent

   2. P(Y = 0) + P(Y = 1) ≈ 0.092.

   3. 1 − [P(Y = 0) + P(Y = 1)] ≈ 0.80.

4. 27.

   1. The larger sample.

   2. Check parts daily.

5. 29.

   1. $10\pm 3\times 5/\sqrt{18}$

   2. $-4\pm 3\times 2/\sqrt{12}$

6. 31.

   1. 0.986573 = 0.9973⁵

   2. 0.763101 = 0.9973¹⁰⁰