On the basis of extensive tests, the yield point of a particular type of mild steel-reinforcing bar is known to be normally distributed with o = 100. The composition of the bar has been slightly modified, but the modification is not believed to have affected either the normality or the value of a. (a) Assuming this to be the case, if a sample of 64 modified bars resulted in a sample average yield point of 8461 lb, compute a 90% CI for the true average yield point of the modified bar. (Round your answers to one decimal place.) | Ib (b) How would you modify the interval in part (a) to obtain a confidence level of 96%? (Round your answer to two decimal places.) The value of z vv should be changed to
Continuous Probability Distributions
Probability distributions are of two types, which are continuous probability distributions and discrete probability distributions. A continuous probability distribution contains an infinite number of values. For example, if time is infinite: you could count from 0 to a trillion seconds, billion seconds, so on indefinitely. A discrete probability distribution consists of only a countable set of possible values.
Normal Distribution
Suppose we had to design a bathroom weighing scale, how would we decide what should be the range of the weighing machine? Would we take the highest recorded human weight in history and use that as the upper limit for our weighing scale? This may not be a great idea as the sensitivity of the scale would get reduced if the range is too large. At the same time, if we keep the upper limit too low, it may not be usable for a large percentage of the population!
![**Statistical Analysis of Yield Points in Steel-Reinforcing Bars**
**Background Information:**
Extensive testing has shown that the yield point of a specific type of mild steel-reinforcing bar follows a normal distribution with a standard deviation (\(\sigma\)) of 100. The composition of the bar underwent slight modifications; however, these changes are not believed to affect the normality or standard deviation.
**Statistical Tasks:**
**(a)** If a sample of 64 modified bars results in an average yield point of 8461 pounds (lb), compute a 90% confidence interval (CI) for the true average yield point of the modified bar. Round your answers to one decimal place.
- Confidence Interval: ( _____ , _____ ) lb
**(b)** To alter the interval in part (a) for a 96% confidence level, determine the new value of \(z\). Round your answer to two decimal places.
- The value of \(z\): The value of \(z\) should be changed to _____.
**Notes:**
- A graph or diagram is not included with the text. The exercise requires computation using statistical methods pertinent to confidence intervals for means in a normally distributed sample.
- Ensure calculations consider sample size, standard deviation, and desired confidence levels for accuracy in the statistical analysis.](/v2/_next/image?url=https%3A%2F%2Fcontent.bartleby.com%2Fqna-images%2Fquestion%2Fa0bb33da-4292-4a51-8799-113a66f1981e%2F8f69d5fd-177c-490b-9938-fe23d887712b%2Fndnr2v_processed.png&w=3840&q=75)
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