Let x be a random variable representing percentage change in neighborhood population in the past few years, and let y be a random variable representing crime rate (crimes per 1000 population). A random sample of six Denver neighborhoods gave the following information. x 31 1 11 17 7 6 y 176 37 132 127 69 53 In this setting we have Σx = 73, Σy = 594, Σx2 = 1457, Σy2 = 73,468, and Σxy = 9905. (a) Find x, y, b, and the equation of the least-squares line. (Round your answers for x and y to two decimal places. Round your least-squares estimates to four decimal places.) x =  y =  b =  ŷ =  +  x

Consider the bivariate distribution for the random variables x and y. The correlation coefficient of x and y is the covariance   a. Consider the bivariate distribution for the random variables x and y. The correlation coefficient of x and y is the covariance   b. multiplied by the product of the standard deviations for x and y.       c. multiplied by the standard deviation of y and divided by the standard deviation of x.   d.  multiplied by the standard deviation of x and divided by the standard deviation of y.

ASK YOUR TEACHER Nationally, about 11% of the total U.S. wheat crop is destroyed each year by hail.t An insurance company is studying wheat hail damage claims in a county in Colorado. A random sample of 16 claims in the county reported the percentage of their wheat lost to hail. 14 7 10 11 12 19 14 11 9 8 23 19 13 7 10 7 The sample mean is x = 12.1%. Let x be a random variable that represents the percentage of wheat crop in that county lost to hail. Assume that x has a normal distribution and a = 5.0%. Do these data indicate that the percentage of wheat crop lost to hail in that county is different (either way) from the national mean of 11%? Use a = 0.01. (a) What is the level of significance? State the null and alternate hypotheses. Will you use a left-tailed, right-tailed, or two-tailed test? O Ho: H = 11%; H,: µ 11%; right-tailed O Ho: H + 11%; H,: u = 11%; two-tailed O Ho: H = 11%; H,: u + 11%; two-tailed (b) What sampling distribution will you use? Explain the rationale for your…

Nationally, about 11% of the total U.S. wheat crop is destroyed each year by hail.† An insurance company is studying wheat hail damage claims in a county in Colorado. A random sample of 16 claims in the county reported the percentage of their wheat lost to hail. 15 7 7 13 13 20 13 12 5 10 26 22 13 7 11 3 The sample mean is x = 12.3%. Let x be a random variable that represents the percentage of wheat crop in that county lost to hail. Assume that x has a normal distribution and σ = 5.0%. Do these data indicate that the percentage of wheat crop lost to hail in that county is different (either way) from the national mean of 11%? Use α = 0.01. (a) What is the level of significance? Compute the z value of the sample test statistic. (Round your answer to two decimal places.)(c) Find (or estimate) the P-value. (Round your answer to four decimal places.)

There are two independent random variables X and Y. X has mean 4 and standard deviation , and Y also has mean 4 and standard deviation . A random variable W is the difference between X and Y. That is, W = X - Y. Calculate the mean of W.

An experiment where a patient's blood pressure is measured before a treatment (call it X;) and after the treatment (call it Y;). The difference in the blood pressue of each patient, Z; = Y; – X; is also recorded. The sample size n of patients is large. Suppose the true population mean of the patient's blood pressure before treatment is 41 and after treatment is 42, both unknown. Suppose the true population variance of the patient's blood pressue before and after treatment are the same, but unknown. Find an approximate 1-a confidence interval for 12 - 41- 2.