Study the following production data of a sugar factory. Year 2001 2002 2003 2004 2005 2006 2007 Production (‘000 tonnes) (y) 76 87 95 81 91 96 90   What is the estimate of the production for 2008 using straight-line trend - with the origin at the year 2001 - by the least-squares method \((\sum x= 0, \sum x^2 = 28, \sum xy = 56) ?\)

Study the following production data of a sugar factory. Year 2001 2002 2003 2004 2005 2006 2007 Production (‘000 tonnes) (y) 76 87 95 81 91 96 90   What is the estimate of the production for 2008 using straight-line trend - with the origin at the year 2001 - by the least-squares method \((\sum x= 0, \sum x^2 = 28, \sum xy = 56) ?\) Correct Answer 102

Given

∑x = 0

∑x2 = 28

∑xy = 56

Formula

a = ∑y/n

b = ∑xy/∑x2

Explanation

Year

y

2001

76

2002

87

2003

95

2004

81

2005

91

2006

96

2007

90

N = 7

∑y = 616

Y = a + bx

⇒ a = 616/7

⇒ a = 88

⇒ b = 56/28

⇒ b = 2

Y = 88 + 2x

⇒ X = 2008 – 2001 = 7

Y = 88 + 2 × 7

∴ estimate of the production for 2008 is 102

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