Bank officers are considering targeting young parents with an offer to start a college savings plan.
They have decided to pursue this new marketing program only if at least 30% of such parents might be interested in this kind of plan. They surveyed 250 randomly selected parents, of whom 38% indicated some interest. Which formula below correctly computes the z-score they should use to see if this survey result provides evidence that the true proportion is over 30%?
(A)
0.38
- 0.30
~ =
(B)
0.30 - 0.38
(0.30) (0.70)
(C)
0.38 - 0.30
2 =
(0.38) (0.62)
250
(D)
0.38 - 0.30
2 =
v250(0.30) (0.70
(E)
0.30 - 0.38
2 = v250(0.38)(0.62)