According to a Gallup poll conducted April 3–6, 2014, 21% of Americans aged 18 t
ID: 3217060 • Letter: A
Question
According to a Gallup poll conducted April 3–6, 2014, 21% of Americans aged 18 to 29 said that college loans and/or expenses were the top financial problem facing their families. Suppose that this poll was based on a random sample of 1450 Americans aged 18 to 29.
a. What is the point estimate of the corresponding population proportion?
b. Construct a 95% confidence interval for the proportion of all Americans aged 18 to 29 who will say that college loans and/or expenses were the top financial problem facing their families. What is the margin of error for this estimate?
Please show ALL work and explain the steps!!! I will rate:)
Explanation / Answer
a) the sample proportion p is a point estimate of the population proportion P.
Point estimate = 21%
b) for 95% confidence interval z value = 1.96
CI = p + / -z * sqrt( p( 1-p)/n)
= 0.21 + /- 1.96 * sqrt ( .21 * .79/ 1450)
= (0.189 , 0.231)
Margin of error = z * sqrt( p( 1-p)/n)
= 1.96 * sqrt ( .21 * .79/ 1450)
= 0.021
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