in 2004, an environmental research group studied the performance of truss and frame structures subjected to uncertain loads. the load was assumed to have a normal distribution with a mean of 20 pounds. Also, the probability that the load is between 16 and 24 pounds is 0.34. On the basis of this information, find the variance of the load distribution.
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The summary results are given below: Male MBA Graduates: Sample mean = $85500, Sample standard deviation = 10000, Sample size = 50 Female MBA Graduates: Sample mean = $78000, Sample standard deviation = 8000, Sample size = 50 Assuming that the populations are normally distributed and the population variances from both populations are equal, is there evidence that the average starting salary of the male MBA graduates is higher than the average starting salary of the female MBA graduates? Use a 0.05 level of significance. (a) State the null and alternative hypothesis for this problem. (b) What is the value of the pooled-variance tSTAT test statistic for this problem? (c) Using the level of…A study was undertaken to compare the average high-density lipoprotein (HDL) levels of normal and obese adults in a certain community. HDL levels of a random sample of adults from this community were measured (in milligrams per deciliter or mg/dL) and presented below. Assume that the HDL levels of both the normal and obese adults follow the normal distribution with unknown but equal population variances. Is there a significant difference between the average HDL levels of normal and obese adults? Use a 5% level of significance.For a standardized psychology examination, the scores have a mean of 500 and a variance of 9475. It is hypothesized that the variance, o, of scores for psychology majors on this exam is lower than 9475. A random sample of 26 exams completed by psychology majors had a mean of 509 and a variance of 3987. Assuming that scores among psychology majors on this exam are approximately normally distributed, may we conclude, at the 0.01 level of significance, that the hypothesis is correct? Perform a one-tailed test. Then complete the parts below. Carry your intermediate computations to three or more decimal places and round your answers as specified below. (If necessary, consult a list of formulas.) (a) State the null hypothesis H, and the alternative hypothesis H,. H, :0 H :0 (b) Determine the type of test statistic to use. OSO (Choose one) ▼ (c) Find the value of the test statistic. (Round to three or more decimal places.) ODefine the bias of an arbitrary estimator and show that if an estimator is unbiased then the square error is equal to its variance.A school administrator wants to see if there is a difference in the number of students per class for Portland Public School district (group 1) compared to the Beaverton School district (group 2). Assume the populations are normally distributed with unequal variances. A random sample of 28 Portland classes found a mean of 36 students per class with a standard deviation of 5. A random sample of 27 Beaverton classes found a mean of 35 students per class with a standard deviation of 6. Find a 90% confidence interval in the difference of the means. 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