Question

Find the sample size necessary in order to be 95% confident when determining the true mean weight within 2 units (EC2). Assume that sample variance is 44. a. 65 b. 157 c. 43 d. 170 e. 89

Answer 1

Answer:

(c) 43.

Step-by-step explanation:

Given:

Margin of error (E) = 2

Sample variance $(s^{2})$ = 44

Confidence level = 95%

The z- value at 95% confidence level is 1.96.

The sample using the provided information can be calculated as:

$n=(\frac{z(s)}{E})^{2} \\n=\frac{z^{2} s^{2} }{E^{2} } \\n=\frac{1.96^{2} (44) }{2^{2} }\\n= 42.52\\n=43$

Hence, the correct option is (c) 43.