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In: Statistics and Probability

Let x be per capita income in thousands of dollars. Let y be the number of...

Let x be per capita income in thousands of dollars. Let y be the number of medical doctors per 10,000 residents. Six small cities in Oregon gave the following information about x and y.

x 9.0 9.4 10.2 8.0 8.3 8.7
y 9.5 18.0 21.2 10.2 11.4 13.1

Complete parts (a) through (e), given Σx = 53.6, Σy = 83.4, Σx2 = 481.98, Σy2 = 1269.3, Σxy = 761.13, and r ≈ 0.864.

(b) Verify the given sums Σx, Σy, Σx2, Σy2, Σxy, and the value of the sample correlation coefficient r. (Round your value for r to three decimal places.)

Σx =
Σy =
Σx2 =
Σy2 =
Σxy =
r =


(c) Find x, and y. Then find the equation of the least-squares line  = a + bx. (Round your answers for x and y to two decimal places. Round your answers for a and b to three decimal places.)

x =
y =
= + x

(e) Find the value of the coefficient of determination r2. What percentage of the variation in y can be explained by the corresponding variation in x and the least-squares line? What percentage is unexplained? (Round your answer for r2 to three decimal places. Round your answers for the percentages to one decimal place.)

r2 =
explained     %
unexplained     %


(f) Suppose a small city in Oregon has a per capita income of 9.8 thousand dollars. What is the predicted number of M.D.s per 10,000 residents? (Round your answer to two decimal places.)   _________________M.D.s per 10,000 residents

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