Question

Check your skills CHECK YOUR SKILLS 5.20 Figure 5.10 is a scatterplot of school GPA against 1Q test scores for 15 seventh-grade students. The line is the least-squares regression line for predict- ing school GPA from IQ score. If another child in this class has IQ score 110, you predict the school GPA to be close to y (in cubic feet) to heat the home and outside tem perature x (in degree-days, where a day's degree-days are the number of degrees its average temperature falls below 65'F) over a 23-month period. He then com puted the least-squares regression line for predicting y from x and found it to be (a) 2 (b) 7.5 ic) 11. j-85+ 16x How much, on average, does gas used increase for each additional degree-day! (a) 23 cubic feet (c) 16 cubic feet .26 According to the regression line in Exercise 5.25, the predicted amount of gas used when the outside tem- peranure is 20 degree-days is about (a) 405 cubic feet (b) 85 cubic feet 10 b) 320 cubic feet (c) 105 cubic feet By looking at the equation of the least-squares re- geaion line in Exercise 5.25, you can see that the comrelation between amount of gas uned and degree- days is 5.27 300 1Q test score FIGURE S.10 Sctept of Q so Esees 520 nd521 (a) greater than seno 6 less than eno (d unable so be determined without seeing the data 5.28 The wware used to compute the least-squares re- gression line in Exercise 5.25 says that -098. Thi rsts that (al although degee-days and ge used are comelated deg-ays do not predict gas used very accurately ) g used inceases by VO98-099 cabic feet for each adltnal degree day d prediction of ged fom degree-days will be nd schoot GPS 5.21 The dope of the line in Figre 5,10 closest so )02 (al-1 5.22 The points on a scatte lie close . The dope of the line i (b) his matr He began with the whose ta 4 5.23 ed keees he sng $1000 fom his mothet and adde 5100 each seas His total savingsy after s yeats are gen by the egatin ialy1000100 0y-100+ 1000 )y-1000+ 5.24 Sokens de't bee a g n the averag) a okens, and heavy smckens don't lve a long fiht Mickens You rerss the age at death of s quite accura 5.29 Rescanchers measured the percent body fat and the prefered amount of salt (percent weighe veume 6r several children. Here are data for seven children sT d anot of salt s h 02 03 04 0s 06 08 L 20 30 22 323 0 Pee bode for y ale sckers the number of packs per day they The sope of wour eeessn lne Ue yr calculanor or soware what i the eqcion d the least-sguares egession ine for peedicting per- cen body fat dom pefened amoun of salt a5-242+60 a5-015+0.01 idj-60+24.2x al will gheater than 0 les than determined withot seeng the data home in the Madwest intalled olar reduce heating costs, Afer intalling the panels, he mcasred the amont of natual gs ned 5.25 An School GPA

Answer 1

5.20. b) 7.5

5.21 b) 0.2

5.22. c) -3

5.23 a) y= 1000 + 100x.

5.24. a) will be greater than 0 ( as the number of packs increases the number of deaths also increases)

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