## anonymous one year ago Please I really need help Can someone help me if I type it all out? Posts longer than 2 sentences on here seem to scare people on here, but I will fan and medal.

1. arindameducationusc

which data?

2. arindameducationusc

regression, never tried. But I am good with equations and straight lines I will try

3. anonymous

I am going to type it, I seem to keep scaring people off with my table and work.

4. anonymous

I'm just going to lay it all out okay?

5. arindameducationusc

haha

6. anonymous

that's all my work

7. arindameducationusc

okay.... I will try okay.. I cant guarantee, but I will do my best

8. anonymous

9. arindameducationusc

Are you taking x as 'avrge weekly paycheck'?

10. anonymous

yes

11. anonymous

@peachpi can you help at all?

12. arindameducationusc

Rate of change are absolutely correct, ya but the graph...!! hmmm... let me think.....

13. anonymous

the line regression has to be least squares or line of best-fit

14. arindameducationusc

@lostinrome Is your cell phone android... I can give you a name of a software which deals with regressions

15. anonymous

I'm on my laptop right now

16. anonymous

^ I was just going to ask if this has to be done by hand. Excel does linear regression

17. anonymous

yeah I have to come up with an equation (this whole thing is all on paper)

18. arindameducationusc

I graphed it in my mobile, should I send you the screen shot?

19. anonymous

I'm not sure where to even start the linear regression and how I get an equation from it

20. arindameducationusc

equation I am getting -1.951402x+1040.6445224

21. anonymous

I haven't done this in years. I'm looking some equations up

22. anonymous

I don't have excel on my laptop so I can't use that

23. arindameducationusc

@phi is a very helpful person. He will help once he is online, just keep the question open

24. anonymous

this is bad I really don't know what to do and I'm like freaking out

25. anonymous

when does @phi come on usually?

26. arindameducationusc

Don't know actually, but he will help. He has helped me a lot in my complicated problems!

27. anonymous

Fill in the table. In the third column, square the x values. In the fourth, multiply x and y. Add up the numbers in each column for the box at the bottom |dw:1440211191451:dw|

28. anonymous

okay let me see

29. anonymous

yes

30. anonymous

Once we have the table filled in these are the formulas we're going to use to write the line in y = ax + b format |dw:1440211851554:dw|

31. anonymous

i'm still typing in the table so give me a sec

32. anonymous

|dw:1440211921215:dw|

33. anonymous

okay now to write the line in y = ax + b format

34. anonymous

so how do we apply the table to those formulas

35. anonymous

I've seen those formulas before, but have a hard time understanding them.

36. anonymous

ok so now we're going to use the sums at the bottom of the table. To put each sum in the right place, you just need to pay attention to the x's and y's and their exponents n is the number of points, so $$n = 6$$ $\sum_{i=1}^{6}x_i=96$ $\sum_{i=1}^{6}y_i=5695$ $\sum_{i=1}^{6}x^2_i=1606$ $\sum_{i=1}^{6}x_iy_i=99055$ Putting all that into the equation for a we get $a=\frac{ 6(99055)-(96)(5695) }{ 6(1606)-(96)^2 }$

37. anonymous

okay that makes sense

38. anonymous

a = 1587/14 ?

39. anonymous

yes :)

40. anonymous

now for b $b=\frac{ 1 }{ 6 }\left( 5695-\frac{ 1587 }{ 14 }(96) \right)$

41. anonymous

At this point you might find it easier to change these to decimals and round to 2 or 3 decimal places

42. anonymous

I'm having trouble finding the decimal for b

43. anonymous

b=(1/6)(5695-10882.29) =(1/6)(5187.29) = -864.55

44. anonymous

yeah

45. anonymous

y = 113.35x + -864.55

46. anonymous

what do i do for the x in there?

47. anonymous

the x stays. It's part of the equation

48. anonymous

okay thought so. Wait was this whole thing in least squares or line of best-fit?

49. anonymous

least squares

50. anonymous

from excel |dw:1440214055244:dw|

51. anonymous

okay and now for my millionth question, I have to get the slope of this equation we came up with and compare to the rate of change values I did.

52. anonymous

I'm going to try and find the slope.

53. anonymous

The slope is the "a" we found 113.36

54. anonymous

oh slope of y = 113.35x + -864.55 is 113.36? Okay

55. anonymous

oh, ok. it should have been rounded up to 113.36

56. anonymous

so slope is 113.36

57. anonymous

Yes. And for the rates of change you found above, you ended up with the right results, but the equations are backwards. For example the first one should be m= (810 - 585)/(15-13) m = 225/2 m = 112.5

58. anonymous

Oh one more thing if you don't mind or if @arindameducationusc can pitch in if @peachpi is tired of me lol

59. arindameducationusc

hehe :D

60. anonymous

It looks like the x's were years of schooling, so plug in 23 for x in the equation you found and solve for y

61. anonymous

right

62. anonymous

You are awesome. Thank you again!

63. anonymous

I want to give you like 50 medals

64. anonymous

lol you're welcome

65. anonymous

yeah that's the right formula. Maybe you just typed them in reverse up top, because you ended up with the right numbers at the end

66. anonymous

Yeah looking back I think that's what happened.

67. anonymous

ok cool

68. anonymous

:)