Question

A random sample of 28 items is drawn from a population whose standard deviation is unknown. The sample mean is x=900 and the sample deviation is s = 10. Use appendix D to find the values of student's t. (a) Construct an interval estimate of u with 98% confidence. (Round your answers to 3 decimal places.)

Answer 1

Answer:

795.596≤u≤804.403

Step-by-step explanation:

Confidence interval is expressed using the formula;

CI = xbar ± (z*s/√n)

xbar is the sample mean

z is the z score at 98% confidence

s is the standard deviation

n is the sample size

Given

xbar = 800

z = 2.33

s = 10

n = 28

Substitute into the formula;

CI =800 ± (2.33*10/√28)

CI = 800 ± (2.33*10/5.2915)

Ci = 800± (2.33* 1.8898)

CI = 800 ± 4.4033

CI = (800-4.4033, 800 + 4.4033)

CI = (795.596, 804.403)

Hence an interval estimate of u with 98% confidence is expressed as

795.596≤u≤804.403