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You plan to conduct a survey to find what proportion of the workforce has two or more jobs. You decide on the 95% confidence level and a margin of error of 2%. A pilot survey reveals that 5 of the 50 sampled hold two or more jobs.

How many in the workforce should be interviewed to meet your requirements? (Round up your answer to the next whole number.)


Sagot :

Answer:

865 in the workforce should be interviewed to meet your requirements

Step-by-step explanation:

In a sample with a number n of people surveyed with a probability of a success of [tex]\pi[/tex], and a confidence level of [tex]1-\alpha[/tex], we have the following confidence interval of proportions.

[tex]\pi \pm z\sqrt{\frac{\pi(1-\pi)}{n}}[/tex]

In which

z is the z-score that has a p-value of [tex]1 - \frac{\alpha}{2}[/tex].

The margin of error is given by:

[tex]M = z\sqrt{\frac{\pi(1-\pi)}{n}}[/tex]

A pilot survey reveals that 5 of the 50 sampled hold two or more jobs.

This means that [tex]\pi = \frac{5}{50} = 0.1[/tex]

95% confidence level

So [tex]\alpha = 0.05[/tex], z is the value of Z that has a p-value of [tex]1 - \frac{0.05}{2} = 0.975[/tex], so [tex]Z = 1.96[/tex].

How many in the workforce should be interviewed to meet your requirements?

Margin of error of 2%, so n for which M = 0.02.

[tex]M = z\sqrt{\frac{\pi(1-\pi)}{n}}[/tex]

[tex]0.02 = 1.96\sqrt{\frac{0.1*0.9}{n}}[/tex]

[tex]0.02\sqrt{n} = 1.96\sqrt{0.1*0.9}[/tex]

[tex]\sqrt{n} = \frac{1.96\sqrt{0.1*0.9}}{0.02}[/tex]

[tex](\sqrt{n})^2 = (\frac{1.96\sqrt{0.1*0.9}}{0.02})^2[/tex]

[tex]n = 864.4[/tex]

Rounding up:

865 in the workforce should be interviewed to meet your requirements