Battery lifetimes. In February 2019, the Android Authority website reported the effectiveness of battery life

(in minutes) with different display sizes (inches) between 1080p and 1440p resolution (https://www.androidauthority

.com/does-1440p-affect-battery-life-947778/).

Dependent variable is: Battery life R-squared = 6.29%

s = 231.0582 with 10 - 1 = 9 degrees of freedom Variable Coeff SE (Coeff) t-stat P-value Intercept -1334.1756 2820.9188 -0.4730 0.6489 Size (inches) 334.3756 456.2324 0.7329 0.4845

a) How many devices were tested?

b) Are the conditions for inference satisfied? Explain.

c) Is there evidence of an association between display size and battery life? Test an appropriate hypothesis, and state your conclusion.

d) Is the association strong? Explain.

e) What is the equation of the regression line?

f) Create a 95% confidence interval for the slope of the true line.
g) Interpret your interval in this context.

Transcribed Image Text:

Residual Battery Life Time (minutes) 1400 1200 1000 800 600 400 200 Battery Life Time (Minutes) 0 5.95 6 6.05 6.1 6.15 6.2 6.25 6.3 6.35 6.4 6.45 Display Sizes (inches) Residuals 400 300 200 100 0 660 680 700 720 740 760 780 800. 820 -100 -200 -300 -400 Predicted Battery Life Time (minutes)