(15 points) 3) A civil engineer is analyzing the compressive strength of concret

Question

(15 points) 3) A civil engineer is analyzing the compressive strength of concrete. A random sample of 10 specimens has a mean compressive strength of 3010.22 psi. Assume the population standard deviation is 900 psi. How many more samples are required to find the compressive strength to within 50 psi at 99% confidence? (10+7+5 Points) A simple linear regression model based on 20 observations. The F-stat for the model is 21.44 and the SSE is 1.41. The standard error for the coefficient of X is 0.2. 4) a) Complete the ANOVA table. b) Find the t-stat of the co-efficient of X. What is the p-value for the statistical significance of this variable? Find the co-efficient of x. c)

Explanation / Answer

(3)

Data provided is as follows:

Sample size n = 10

Sample mean m = 3010.22

Population Standard deviation S = 900

Margin of error ME = 50

For a 99% CI, the margin of error is:

ME = 2.58*(S/(n^0.5))

50 = 2.58*(900/(n^0.5))

Solving we get:

n = 2157

So, number of more samples required = 2157-10 = 2147 more samples

Related Questions

Navigate

• Browse (All)
• Browse #
• Subjects

---

---

Integrity-first tutoring: explanations and feedback only — we do not complete graded work. Learn more.