Answer:
Option C: n = 32; p^ = 0.4
Step-by-step explanation:
The normal curve can be used in this case if; np ≥ 10 or n(1 - p) ≥ 10
A) For n = 28 and p = 0.3;
np = 28 × 0.3 = 8.4 < 10
Thus, it can't be used.
B) For n = 28 and p = 0.9;
np = 28 × 0.9 = 25.2 > 10 Ok
n(1 - p) = 28(1 - 0.9) = 2.8 Not Ok
Thus, it can't be used
C) For n = 32 and p = 0.4
np = 32 × 0.4 = 12.8 > 10 Ok
n(1 - p) = 32(1 - 0.4) = 19.2 > 10 Ok
Thus, it can be used
D) For n = 32 and p = 0.2
np = 32 × 0.2 = 6.4 < 10 Not Ok
Thus it can't be used.
