Question

In: Statistics and Probability

A pollster wishes to estimate, with 99% confidence, the proportion of people who believe the United...

A pollster wishes to estimate, with 99% confidence, the proportion of people who believe the United States should pursue a more aggresive foreign policy.


Find the minimum sample size necessary to achieve a margin of error of less than 2%.

  1. Assuming no previous estimates are available. Round your answer up to the next integer.


  2. Assuming a previous estimate of 0.35. Round your answer up to the next integer.

Solutions

Expert Solution

Solution :

a)

= 0.5

1 - = 0.5

margin of error = E = 0.02

Z/2 = 2.576

sample size = n = (Z / 2 / E)2 * * (1 - )

= (2.576 / 0.02)2 * (0.5 * 0.5)

= 4148

Minimum sample size is required = 4148

b)

= 0.35

1 - = 0.65

margin of error = E = 0.02

Z/2 = 2.576

sample size = n = (Z / 2 / E)2 * * (1 - )

= (2.576 / 0.02)2 * (0.35 * 0.65)

= 3775

Minimum sample size is required = 3775


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