assignment9

The defective percentage of bricks produced by a certain process is 20%. A new method isintroduced which is supposed to reduce the defective percentage. 150 bricks produced by thismethod showed 27 of them are defective. Does this data support the above claim at significancelevela = 0.01?

A researcher is using a two-tailed hypothesis test with α = .05 to evaluate the effect of a treatment. If the boundaries for the critical region are t = ± 2.080, then how many individuals are in the sample? Group of answer choices

What is the kurtosis for a distribution with a mean of 12.00 and a mode of 12.00?

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What is the kurtosis for the distribution of scores with a mean of 9.02 and a mode of 3?

Your hypothesis test for a mean with n = 18 has a two-tailed critical region. The test statistic is tt = -1.38. Find the p-value accurate to 2 decimal places.

A Rollercoaster’s auditors estimate that the average daily loss from those illegally riding without tickets is more than $300, but wants to determine the accuracy of this statistic.  The company researcher takes a random sample of losses over 64 days and finds that = $298 and s = $25.   a) Test at α = 0.05. Be sure you cover all steps: hypothesis, critical value, acceptance range, conclusion.     b) (Unrelated to a’s results) Construct a 90% confidence interval of losses.

The time required to start a​ business, defined as the number of days needed to complete the procedures to legally operate a​ business, in 20 developed countries and 20 emerging countries is included in the accompanying table. Assuming that the population variances for developed countries and emerging countries are​ equal, is there evidence of a difference in the mean time required to start a business between developed countries and emerging​ countries? (Use α=0.05​.) Let μ1 be the mean time required to start a business in developed countries and let μ2 be the mean time required to start a business in emerging countries. What are the null and alternative​ hypotheses?   A. H0​: μ1=μ2      H1​: μ1≠μ2   B. H0​: μ1≠μ2      H1​: μ1=μ2   C. H0​: μ1≥μ2      H1​: μ1<μ2   D. H0​: μ1≤μ2      H1​: μ1>μ2   t-stat=___ p-value=___   What is the correct​ conclusion?   A. Reject H0. There is insufficient evidence of a difference in mean time required to start a…

In a random sample of 85 automobile engine crankshaft bearings, 10 have a surface finishroughness that exceeds the specifications. Do these data present strong evidence that theproportion of crankshaft bearings exhibiting excess surface roughness exceeds 0.10?State and test the appropriate hypotheses using α = 0.05.

Empirical attention span studies established that college students’ attention span is normally distributed for about 20 ± 2.5 minutes (µ ± σ). However, during Covid-19 pandemic, many studies reported that college students’ attention span has been shorten. To verify this information, a neuropsychologist conducts an experiment to measure the attention span for a sample of college students. The data were recorded as below:   9, 10, 12, 17, 19, 20, 13, 15, 14, 11   What is the probability that we made a Type I error? What would this probability be in terms of the independent and dependent variables? Is there a risk of a Type II error?

Empirical attention span studies established that college students’ attention span is normally distributed for about 20 ± 2.5 minutes (µ ± σ). However, during Covid-19 pandemic, many studies reported that college students’ attention span has been shorten. To verify this information, a neuropsychologist conducts an experiment to measure the attention span for a sample of college students. The data were recorded as below:   9, 10, 12, 17, 19, 20, 13, 15, 14, 11        A- What is the dependent variable? B- What is the level of measurement of the dependent variable? c- Is there a significant difference in attention span between the sample and the general college student population? Test at the alpha = .01 level. D- Compute Cohen’s d

Where are the critical region(s) located in a z-distribution if a one-tailed hypothesis test was conducted to see if a treatment led to a decrease using an alpha = 0.0668 Report the complete z-score (no rounding)

An experiment to compare the spreading rates of five different brands of yellow interior latex paint available in a particular area used 4 gallons (J = 4) of each paint. Suppose that all require assumptions are satisfied. The sample average spreading rates (ft-/gal) for the five brands were x1 = 462.0, X2. = 512.8, x3 = 437.5, x4. 469.3, and X5. = 532.1. The computed value found to be significant at level a = 0.05. With MSE 220.8, use Tukey's procedure to investigate significant differences between brands. (Round your answer to two decimal places.) %3D W = Which means differ significantly from one another? (Select all that apply.). and

Determine the critical z-score corresponding to αα = 0.15 in a left-tail test. crititical z-score =     [three decimal accuracy]

Researchers conducted a study to determine whether magnets are effective in treating back pain. The results (higher values indicate larger reductions in pain levels) are shown in the table for the treatment (with magnets) group and the sham (or placebo) group. treatment sham sample size 19 22 mean 12 10 standard deviation 4 Assume that the two samples are independent simple random samples selected from normally distributed populations, and do not assume that the population standard deviations are equal. Use the critical value method and a 0.10 significance level to test the claim that the treatment mean measure of reduction in back pain is equal to the sham mean measure of reduction in back pain. (Hint: Consider statistictreatment-Statisticsham-) Enter the smallest critical value. (Round your answer to nearest thousandth.)

What is th enull and alt. hypothesis? the test statistic? the P-value? What is the conclusion?

A random sample of 46 adult coyotes from Northern Minnesota showed the average age to be sample mean of 2.05 years. The population standard deviation is known to be o = 1.13 years However, it is thought that the average age of coyotes is µ = 1.75 yearstest to see if the coyotes in Northern Minnesota live longer than the national average of 1.75 years. Use 0.03 level of significance. When using the classical approach, whạt is the critical region (step 3)? Anything less than or equal to z = 1.80 O Anything less than or equal to z = 1.88 O Anything greater to or equal to z = 1.88 O Anything greater to or equal to z = 1.80

6.75 Suppose that there are 6 deaths due to bladder can- cer among workers in a tire plant from 1/1/64 to 12/31/83, while 1.8 are expected based on U.S. mortality rates. Pro- vide a 95% CI for the expected number of deaths from bladder cancer over 20 years among the tire workers. Is the number of cases of bladder cancer in this group excessive?

A random sample of n = 100 observations produced a mean of z = 31 with a standard deviation of s = 3. %3D %3D (a) Find a 99% confidence interval for u Lower-bound: Upper-bound: (b) Find a 90% confidence' interval for u Lower-bound: Upper-bound: (c) Find a 95% confidence interval for u Lower-bound: Upper-bound:

The population standard deviation is unknown, the α=0.01 in a two tailed test with a n=301.)Degrees of Freedom= 2.)The crtitical value for the rejection region is tc=±(Round to 3 decimal places)

uestion 34. After having made a decision on the test at the significance of a = 0.05, the most ppropriate conclusion in the context of research is A) There is not any significant difference between the species with respect to population mean brain eptide content. B) There is a significant difference between the species with respect to population mean brain peptide ontent. C) The population mean brain peptide content of skate fish is significantly greater than that of dogfish. D) The population mean brain peptide content of skate fish is not significantly greater than that of dogfish. E) The population mean brain peptide content of skate fish is exactly the same as that of dogfish. Questions 35-36. The information about head sizes was collected over 18 pilots to determine the feasibility of using cheap cardboard callipers to make the measurements, instead of metal ones which were expensive and uncomfortable. The head size of each pilot was measured once using a cardboard calliper and…

Determine the critical value zα/2zα/2 that corresponds to a 96% level of confidence.