Question

Maureen Mcllvoy, owner and CEO of a mail order business for wind surfing equipment and supplies, is reviewing the order filling operations at her warehouses. Her goal is 100% of orders shipped within 24 hours. In previous years, neither warehouse has achieved the goal, but the East Coast Warehouse has consistently out-performed the West Coast Warehouse. Her staff randomly selected 200 orders from the West Coast Warehouse (population 1) and 400 orders from the East Coast Warehouse (population 2), and reports that 190 of the West Coast Orders were shipped within 24 hours, and the East Coast Warehouse shipped 356 orders within 24 hours. Assuming a = 0.05, the observed 2 value is -3.15 1.05 2.42 1.53 0.95

Answer 1

For sample 1, we have that the sample size is N1 = 200, the number of favorable cases is X1 190, so then the sample proportion is h = * = 200 = 0.95 For sample 2, we have that the sample size is No = 400, the number of favorable cases is Xo = 356, so then the sample proportion is p2 = x3 = 358 = 0.89 The value of the pooled proportion is computed as = x+X 0.91 190+356 200+400 =

The Z-statistic is computed as follows: Pi - P2 (1 - •)(1/nı+1/n2) 0.95 -0.89 0.91 . (1 -0.91) (1/200+ 1/400) 2.421

The observed z value is = 2.42

Answer : 2.42