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

(c) 43.

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=((z(s))/(E))^(2) \\n=(z^(2) s^(2) )/(E^(2) ) \\n=(1.96^(2) (44) )/(2^(2) )\\n= 42.52\\n=43`

Hence, the correct option is (c) 43.