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Consider the following data of expenses (in lakhs) of an organization year wise

Year20012002200320042005
Expenses (Rs. lakh)160185220300510

Then expected expenses trends for the year 2006 using method of least square is:

Solution

✅ Correct Option: 4

To find the trend line that best fits the expense data, the years are coded to simplify calculations. Using 2003 as the middle year (coded as 0), the coding is: -2, -1, 0, 1, 2.

YearX (Coded)Y (Expenses in lakhs)XYX²
2001-2160-3204
2002-1185-1851
2003022000
200413003001
2005251010204

ΣX=0\Sigma X = 0

ΣY=1375\Sigma Y = 1375

ΣXY=815\Sigma XY = 815

ΣX2=10\Sigma X^2 = 10


The trend line equation is Y=a+bXY = a + bX where:

b=ΣXYΣX2b = \dfrac{\Sigma XY}{\Sigma X^2}

b=81510b = \dfrac{815}{10}

b=81.5b = 81.5

a=ΣYna = \dfrac{\Sigma Y}{n}

a=13755a = \dfrac{1375}{5}

a=275a = 275

Therefore, the trend line equation is:

Y=275+81.5XY = 275 + 81.5X


For the year 2006, continuing the coding pattern gives X=3X = 3.

Y=275+81.5(3)Y = 275 + 81.5(3)

Y=275+244.5Y = 275 + 244.5

Y=519.5Y = 519.5

The expected expenses for 2006 is Rs. 519.5 lakh.

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