Question

and for 2. A random sample of n measurements is selected from a population with unknown mean known standard deviation o = 10. Calculate the width of a 95% confidence interval for these values of n: a. n=100 b. n=200 c. n=400 d. n=1000 e. n=2000

Answer 1

The following expression to compute the confidence interval for the mean is used:

-:1- (x-xxx+ *)

The width of the confidence interval is given by:

Width = 2 * Z*

At 95% confidence interval, the value of Zc = 1.960

→ Width = 2 * 1.960 *

→ Width =

a) n = 100

39.2 → Width = V100 = 3.92

b) n = 200

→ Width = 39.2 : = 2.771858582 V200

c) n = 400

→ Width = 39.2 400 = 1.96

d) n=1000

39.2 → Width = V1000 = 1.239612843

e) n =2000

Width = 39.2 == 0.8765386472 77000

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