In: Statistics and Probability
b. Calculate the probability that 31% or more of the sample will be living in poverty. Assume the sample is collected in such a way that the conditions for using the CLT are met. Upper P left parenthesis Modifying Above p with caret greater than or equals 0.31 right parenthesis equals nothing (Round to three decimal places as needed.)
Solution:
Given ,
p = 0.31 (population proportion)
Let n be the sample size,
Let
be the sample proportion.
The sampling distribution of
is approximately normal with
mean =
= p = 0.31
SD =
=
Find P(
> 0.31)
Observe that 0.321 is mean of the distribution of
.
Since this distribution is normal , it is symmetric about its mean,
Area to left of mean = Area to the right of mean = 1/2 i,e 0.500
So ,
P(
> 0.31) = 0.500