/*! This file is auto-generated */ .wp-block-button__link{color:#fff;background-color:#32373c;border-radius:9999px;box-shadow:none;text-decoration:none;padding:calc(.667em + 2px) calc(1.333em + 2px);font-size:1.125em}.wp-block-file__button{background:#32373c;color:#fff;text-decoration:none} Q20E Lightbulbs of a certain type are... [FREE SOLUTION] | 91影视

91影视

Lightbulbs of a certain type are advertised as having an average lifetime of 750 hours. The price of these bulbs is very favorable, so a potential customer has decided to go ahead with a purchase arrangement unless it can be conclusively demonstrated that the true average lifetime is smaller than what is advertised. A random sample of 50 bulbs was selected, the lifetime of each bulb determined, and the appropriate hypotheses were tested using Minitab, resulting in the accompanying output.

Variable N Mean StDev SE Mean Z P-Value

Lifetime 50 738.44 38.20 5.40 -2.14 0.016

What conclusion would be appropriate for a significance level of .05? A significance level of .01? What significance level and conclusion would you recommend?

Short Answer

Expert verified

For significance level of\(0.05\)reject the null hypothesis.

For significance level of \(0.01\) do not reject the null hypothesis

Step by step solution

01

Step 1:Null hypothesis

The null hypothesis, denoted by H0, is the claim that is initially assumed to be true (the 鈥減rior belief鈥 claim). The alternative hypothesis, denoted by Ha, is the assertion that is contradictory to H0.

The null hypothesis will be rejected in favour of the alternative hypothesis only if sample evidence suggests that H0 is false. If the sample does not strongly contradict H0, we will continue to believe in the plausibility of the null hypothesis. The two possible conclusions from a hypothesis-testing analysis are then reject H0 or fail to reject H0.

02

Hypothesis is reject or not.

The interest of the potential customer is hypothesis \({H_0}:\mu = 750\) versus \({H_a}:\mu < 750\). At the significance level of \(0.05\) it can be concluded that the null hypothesis is to be reject. This is because the null hypothesis is rejected when \(z < - {z_\alpha }\). Since,

\(\begin{array}{l}{z_\alpha } = {z_{0.05}}\\ = 1.645\end{array}\)

And \(z = - 2.14\).

\(z < - {z_\alpha }\), the null hypothesis is rejected and the customer does not continue with the purchase.

However, at significance level of \(0.01\) the null hypothesis is not reject and the customers continue with the purchase. Since,

\({z_\alpha } = {z_{0.01}} = 2.33,\)and \(z = - 2.14\).

\(z < - {z_\alpha }\),so the null hypothesis is not rejected.

The \(0.01\) significance level and the customer should continue with the purchase.

Hence,

For significance level of \(0.05\) reject the null hypothesis.

For significance level of \(0.01\) do not reject the null hypothesis.

Unlock Step-by-Step Solutions & Ace Your Exams!

  • Full Textbook Solutions

    Get detailed explanations and key concepts

  • Unlimited Al creation

    Al flashcards, explanations, exams and more...

  • Ads-free access

    To over 500 millions flashcards

  • Money-back guarantee

    We refund you if you fail your exam.

Over 30 million students worldwide already upgrade their learning with 91影视!

One App. One Place for Learning.

All the tools & learning materials you need for study success - in one app.

Get started for free

Most popular questions from this chapter

Have you ever been frustrated because you could not get a container of some sort to release the last bit of its contents? The article 鈥淪hake, Rattle, and Squeeze: How Much Is Left in That Container?鈥 (Consumer Reports, May 2009: 8) reported on an investigation of this issue for various consumer products. Suppose five \(6.0oz\) tubes of toothpaste of a particular brand are randomly selected and squeezed until no more toothpaste will come out. Then each tube is cut open and the amount remaining is weighed, resulting in the following data (consistent with what the cited article reported):

\(.53,.65,.46,.50,.37.\)

Does it appear that the true average amount left is less than \(10\% \) of the advertised net contents?

a. Check the validity of any assumptions necessary for testing the appropriate hypotheses.

b. Carry out a test of the appropriate hypotheses using a significance level of \(.05\). Would your conclusion change if a significance level of \(.01\) had been used?

c. Describe in context type I and II errors, and say which error might have been made in reaching a conclusion.

For the following pairs of assertions, indicate which with our rules for setting up hypotheses and why (the subscripts 1 and 2 differentiate between quantities for two different populations or samples):

a. H0: 碌= 100, Ha: 碌 > 100

b.H0: 蟽= 20, Ha: \(\sigma \le 20\)

c.H0: p鈮 .25, Ha: p= .25

d.H0: 碌1 - 碌2 = 25, Ha: 碌1 - 碌2 > 100

e.H0: \(S_1^2 = S_2^2\) , Ha: \(S_1^2 \ne S_2^2\)

f.H0: 碌= 120, Ha: 碌= 150

g.H0: 蟽1,/蟽2 =1,Ha: 蟽1,/ 蟽2 鈮1

h.H0p1 鈥 p2 = -.1, Ha: p1 鈥 p2 < -.1

A new design for the braking system on a certain type of car has been proposed. For the current system, the true average braking distance at 40 mph under specified conditions is known to be 120 ft. It is proposed that the new design be implemented only if sample data strongly indicates a reduction in true average braking distance for the new design.

a.Define the parameter of interest and state the relevant hypotheses.

b.Suppose braking distance for the new system is normally distributed with 蟽= 10. Let \(\overline X \) denote the sample average braking distance for a random sample of 36 observations. Which values of \(\overline x \) are more contradictory to H0 than 117.2, what is the P-value in this case, and what conclusion is appropriate if 伪 = .10?

c.What is the probability that the new design is not implemented when its true average braking distance is actually 115 ft and the test from part (b) is used?

For a fixed alternative value 碌鈥, show that \(\beta (\mu ') \to 0\) as \(n \to \infty \) for either a one-tailed or a two-tailed z test in the case of a normal population distribution with known .

Let denote the true average reaction time to a certain stimulus. For a z test of H0: 碌 =5 versus Ha: 碌 > 5, determine the P-value for each of the following values of the z test statistic.

a.1.42 b. .90 c. 1.96 d. 2.48 e. -.11

See all solutions

Recommended explanations on Math Textbooks

View all explanations

What do you think about this solution?

We value your feedback to improve our textbook solutions.

Study anywhere. Anytime. Across all devices.