Question

question 8 of 28
a 90% confidence interval for a proportion is found to be (0.37, 0.43). what is
the sample proportion?
a. 0.39
b. 0.43
c. 0.40
d. 0.41

Explanation:

Step1: Recall the formula for confidence interval for proportion

The confidence interval for a proportion is given by $\hat{p}-E

Step2: Calculate the mid - point

The formula for the mid - point of an interval $(a,b)$ is $\frac{a + b}{2}$. Here $a = 0.37$ and $b=0.43$. So, $\hat{p}=\frac{0.37+0.43}{2}$.

$$
LATEXBLOCK0
$$

Answer:

C. 0.40