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Because of high production-changeover time and costs, a director of manufacturing must convince management that a proposed manufacturing method reduces costs before the new method can be implemented. The current production method operates with a mean cost of \(\$ 220\) per hour. A research study will measure the cost of the new method over a sample production period. a. Develop the null and alternative hypotheses most appropriate for this study. b. Comment on the conclusion when \(H_{0}\) cannot be rejected. c. Comment on the conclusion when \(H_{0}\) can be rejected.

Short Answer

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a. \( H_0 : \mu \geq 220 \), \( H_a : \mu < 220 \). b. New method costs \( \geq \) $220/hour. c. New method costs < $220/hour.

Step by step solution

01

Define Null Hypothesis

The null hypothesis (H_0) represents the status quo or the hypothesis that there is no effect or no difference. In this context, the null hypothesis should claim that the new manufacturing method does not lead to a cost reduction. Thus, we state it as: \( H_0 : \mu \geq 220 \) where \( \mu \) is the mean cost per hour of the new manufacturing method.
02

Define Alternative Hypothesis

The alternative hypothesis (H_a) is what you want to prove or what indicates a significant effect or difference. Here, the alternative hypothesis is that the new manufacturing method leads to a reduction in the production costs. Therefore, it is stated as: \( H_a : \mu < 220 \).
03

Conclusion When Null Hypothesis Cannot Be Rejected

If \(H_0\) cannot be rejected, it implies that the sample data did not provide sufficient evidence to conclude that the new manufacturing method reduces costs. The mean operation cost using the new method is still considered greater than or equal to $220 per hour.
04

Conclusion When Null Hypothesis Can Be Rejected

If \(H_0\) can be rejected, this means the sample data provides enough evidence to support the claim that the new manufacturing method reduces costs. Therefore, the mean production cost under the new method is less than $220 per hour, which supports the director's proposal.

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Key Concepts

These are the key concepts you need to understand to accurately answer the question.

Null Hypothesis
In hypothesis testing, the null hypothesis, often denoted as \(H_0\), is a statement that signifies no effect or no change. It's basically your starting assumption that there is no significant difference or effect present in your context. When it comes to our production cost scenario, the null hypothesis is crucial. It claims that switching to the new manufacturing method does not reduce costs. Specifically, we can express this through the statement: \(H_0: \mu \geq 220\), where \(\mu\) represents the mean hourly cost using the new method.
The null hypothesis effectively holds that the cost per hour remains at or above $220, reinforcing the status quo. By starting with a position of "no change," it sets a benchmark against which we compare any variations resulting from the new method.
Interestingly, the null hypothesis must be simple enough to test accurately. Rejecting or failing to reject \(H_0\) will tell us if there's convincing evidence that something besides the current method might be more beneficial financially.
Alternative Hypothesis
The alternative hypothesis, denoted as \(H_a\), contrasts the null hypothesis. It represents the change or effect you wish to demonstrate. In our manufacturing cost context, the alternative hypothesis posits that the new method reduces the average cost per hour. More formally, we write this hypothesis as: \(H_a: \mu < 220\).

This hypothesis suggests that the new manufacturing method has the potential to operate at a lower cost than the current \(220 per hour. It is what the director is aiming to prove in support of changing the process.
  • To confidently accept \(H_a\), evidence must indicate a cost drop below \)220.
  • Deciding in favor of \(H_a\) suggests a significant positive impact of the new method.
Consequently, the alternative hypothesis is central in driving change, as it essentially questions and seeks to improve upon the standing norms represented by \(H_0\). By providing evidence to support \(H_a\), the director can effectively argue for the new method's adoption based on more efficient cost management.
Cost Analysis
Cost analysis is a critical process in evaluating the financial viability of new proposals like the new manufacturing method. In our context, conducting cost analysis involves comparing the average cost of production per hour using the old and new methods. This is statistically validated through the hypothesis testing process.

  • The goal of the cost analysis is to lean towards implementation only if the new method demonstrates clear cost advantages.
  • Whether \(H_0\) is rejected or not significantly impacts decision-making.
By undertaking a detailed cost analysis, the director can present solid evidence to management about whether the new procedure lowers production costs. Achieving a reduction means rejecting \(H_0\), potentially resulting in considerable savings and efficiencies. Moreover, comprehensive cost analysis ensures that all variables and potential fluctuating expenses are considered. The importance of accurate data and sound statistical methods can't be overstated when aiming for informed, effective decision-making with long-term financial benefits.

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Most popular questions from this chapter

The manager of an automobile dealership is considering a new bonus plan designed to increase sales volume. Currently, the mean sales volume is 14 automobiles per month. The manager wants to conduct a research study to see whether the new bonus plan increases sales volume. To collect data on the plan, a sample of sales personnel will be allowed to sell under the new bonus plan for a one-month period. a. Develop the null and alternative hypotheses most appropriate for this research situation. b. Comment on the conclusion when \(H_{0}\) cannot be rejected. c. Comment on the conclusion when \(H_{0}\) can be rejected.

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On Friday, Wall Street traders were anxiously awaiting the federal government's release of numbers on the January increase in nonfarm payrolls. The early consensus estimate among economists was for a growth of 250,000 new jobs (CNBC, February 3,2006 ). However, a sample of 20 economists taken Thursday afternoon provided a sample mean of 266,000 with a sample standard deviation of 24,000 . Financial analysts often call such a sample mean, based on late-breaking news, the whisper number. Treat the "consensus estimate" as the population mean. Conduct a hypothesis test to determine whether the whisper number justifies a conclusion of a statistically significant increase in the consensus estimate of economists. Use \(\alpha=.01\) as the level of significance.

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