Question

A researcher wishes to estimate the proportion of adults who have high-speed Internet access. What size sample should be obtained if she wishes the estimate to be within 0.03 with 90% confidence if (a) she uses a previous estimate of 0.34?(b) she does not use any prior estimates? n=_____(Round up to the nearest integer.)

Answer 1

Answer:

675 samples

752 samples

Step-by-step explanation:

Given that :

α = 90%

E = 0.03

Previous estimate (p) = 0.34

Estimated sample proportion (n)

n = p *q * (Zcritical /E)

Zcritical = α/2 = (1 - 0.9) /2 = 0.1 / 2 = 0.05

Z0.05 = 1.645 ( Z probability calculator)

q = 1 - p = 1 - 0.34 = 0.66

n = 0.34 * 0.66 * (1.645/0.03)^2

n = 674.70

n = 675

B.) without prior estimate given ;

p and q should have equal probability

Hence ;

p = 0.5 ; q = 0.5

n = 0.5 * 0.5 * (1.645/0.03)^2

n = 751.67361

n = 752