In: Statistics and Probability
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