Solve the problem.
-Suppose you know that the distribution of sample proportions of the residents of one town over 70 years old in samples of 140 residents is normal with a mean of 0.12 and a standard deviation of 0.02. Suppose that you select a sample of 140 residents and find that the proportion of residents over 70 is 0.04. How many standard deviations is the sample proportion above or below the mean of the distribution of sampling proportions?
A)4
B)-0.08
C)-4
D)-0.67

Question

Quizplus · Accepted Answer

To find how many standard deviations the sample proportion is from the mean, use the formula: $Z = \frac{(X - \mu)}{\sigma}$, where $X = 0.04$, $\mu = 0.12$, and $\sigma = 0.02$. Plugging in the values: $Z = \frac{(0.04 - 0.12)}{0.02} = \frac{-0.08}{0.02} = -4$.

Solve the Problem. -Suppose You Know That the Distribution of Sample Proportions of Sample