Section 4.2 solutions
1a) I will let x = 0 represent 1990, and x = 1 represent 1991 and so on
I plotted the points (0, 19358) (1, 19484) (2, 20293) (3, 21499) and (4, 23561)
1b) Follow steps 1 – 3 on the sample problem (using linreg) answer
Answer #1b: y = 1042.1x + 18754.8
1c) r = .945, since r > .80 we say the line is a good fit to represent the data
1d)
1e) plug in 15 for x (we don’t use 2005): y = 1042.1*15 + 18754.8 = 34386.3
Answer #1e: – 34386.3 tons of waste (in thousands)
3a) I plotted the points (10, 139) (20, 149) (30, 157) (40, 175) (50,216) etc
3b) follow steps from introductory problem using linreg
Answer #3b: y = 4.717948718x + 371.93076923
3c) r = .96 since r > .80 we say the line is a good fit to represent the data
3d)
3e) plug in 110 for x: y =4.717948718*110 + 37.93076923
Answer #3e: 557 acres (rounded)
answer 557 acres (rounded)
5a) I plotted the points (6, 1.1) (7, 1.3) (8, 1.4) … (12, 2.3)
5b) follow steps 1-3 on sample problem use linreg
Answer 5b: y = .2x - .142857
5c) r = .9924, since r > .80 we say the line is a good fit to represent the data
5d)
5e) let x = 28 (get this by 2018 – 1990) y = .2*28 - .142857 = 5.457 (round up to 5.5)
Answer #5e: about 5.5 million dollars per year