Find the margin of error for a​ 95% confidence interval for estimating the population mean when the sample standard deviation equals 100​, with a sample size of​ (i) 484 and​ (ii) 1764. What is the effect of the sample​ size?

Respuesta :

Answer: i) M.E = 1.96×100/√484

M.E = 8.91

ii) M.E = 1.96×100/√1764

M.E = 4.67

Therefore, the margin of error decreases as the sample size increases.

Step-by-step explanation:

Margin of error in statistics can be defined as a small amount that is allowed for in case of miscalculation or change of circumstances.

For a statistical data margin of error can be expressed as;

M.E = zr/√n

Given that;

Standard deviation r = 100

Confidence interval = 95%

sample size n1 = 484, n2 = 1764

Z(at 95% confidence interval) = 1.96

i) M.E = 1.96×100/√484

M.E = 8.91

ii) M.E = 1.96×100/√1764

M.E = 4.67

Therefore, the margin of error decreases as the sample size increases.

The margin of error at 95% when sample size n= 484 and 1764 are 8.91 and 4.67 respectively.

From the information, we need to understand that we can use the z-critical value for estimating the margin of error since the population of the sample sizes are too large.

Using the tables, at the z-critical level of 95%, [tex]\mathbf{z_c = 1.960}[/tex]

The margin of error (M.E) can be determined by using the formula:

[tex]\mathbf{M.E =z_c \times \dfrac{\sigma}{\sqrt{n}}}[/tex]

where;

  • [tex]\sigma = 100[/tex]
  • and the sample sizes (n) are 484, 1764.

  • when n = 484;

[tex]\mathbf{M.E =1.96 \times \dfrac{100}{\sqrt{484}}}[/tex]

M.E = 8.91

  • when n = 1764

[tex]\mathbf{M.E =1.96 \times \dfrac{100}{\sqrt{1764}}}[/tex]

M.E = 4.67

Therefore, we can conclude that the margin of error at 95% when sample size n= 484 and 1764 are 8.91 and 4.67 respectively.

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