Question

An Izod impact test was performed on 20 specimens of PVC pipe. The sample mean is x Overscript bar EndScripts equals 1.14 and the sample standard deviation is s = 0.28. Find a 99% lower confidence bound on the true Izod impact strength. Assume the data are normally distributed. Round your answer to 3 decimal places. Entry field with incorrect answer 1.319 less-than-or-equal-to

Answer 1

Answer:

1.791

Step-by-step explanation:

Confidence interval for normal distributions can be stated in the formula

M±zσ where

• M is the sample mean, which is 1.14

• z is the corresponding z-score for 99% confidence (one-tailed), which is 2.326
• σ is the standard deviation of the sample, which is 0.28

Thus, 99% lower confidence bound on the true Izod impact strength is

1.14+(2.326*0.28) = 1.791