In an article in IEEE Transactions on Instrumentation and Measurement (2001, Vol. 50, pp. 986€“990), researchers reported on a study of the effects of reducing current draw in a magnetic core by electronic means. They measured the current in a magnetic winding with and without the electronics in a paired experiment. Data for the case without electronics are provided in the Table E11-9.

(a) Graph the data and fit a regression line to predict current without electronics to supply voltage. Is there a significant regression at α = 0.05? What is the P-value?

(b) Estimate the correlation coefficient.

(c) Test the hypothesis that ρ = 0 against the alternative ρ ‰  0 with α = 0.05. What is the P-value?

(d) Compute a 95% confidence interval for the correlation coefficient.

TABLE 11-8 Weight and Blood Pressure Data

TABLE 11-9 Voltage and Current Data

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Systolic BP Systolic BP Subject Weight Subject Weight 1 165 130 14 172 153 2 167 133 15 159 128 3 180 150 16 168 132 155 4 128 17 174 149 212 151 18 183 158 215 6. 175 146 19 150 190 150 20 195 163 210 140 21 180 156 200 124 148 22 143 10 149 125 23 240 170 11 158 133 24 235 165 192 12 169 135 25 160 187 13 170 150 26 159 Current Without Electronics Supply Voltage (mA) 0.66 7.32 1.32 12.22 1.98 16.34 2.64 23.66 3.3 28.06 3.96 33.39 4.62 34.12 3.28 39.21 5.94 44.21 6.6 47.48