(5.36) A study of class attendance and grades among first-year students at a sta
ID: 2921395 • Letter: #
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(5.36) A study of class attendance and grades among first-year students at a state university showed that in general students who attended a higher percent of their classes earned higher grades. eBook Class attendance explained 49 of the variation in grade index among the students. What is the numerical value of the correlation between percent of classes attended and grade index? O 0.2 O -0.04 0.0016 0.04 O-0.2 O -0.0016 (5.25) An owner of a home in the Midwest installed solar panels to reduce heating costs. After installing the solar panels, he measured the amount of natural gas used y (in cubic feet) to heat the home and outside temperature x (in degree days, where a day's degree-days are the number of degrees its average temperature falls below 65 degrees F) over a 23-month period. He then computed the least-squares regression line for predicting y from x and found it to be y=85+ 16x How much, on average, does gas used increase for each additional degree-day? eBook 85 cubic feet O 23 cubic feet O 16 cubic feetExplanation / Answer
Q 5.25.
calculation procedure for regression
mean of X = X / n
mean of Y = Y / n
(Xi-Mean)*(Yi-Mean) = 43.33333
b1 = (Xi-Mean)*(Yi-Mean) / (Xi - Mean)^2
bo = Y / n - b1 * X / n
value of regression equation is, Y = bo + b1 X
=> y = 85 + 16 x
where x is the independent variable &
and from the equation, y is the dependent variable & for evry unit of 'x' the value
of 'y' is increased by 16
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