Question

If y = a + b(x − 2005) fits the time series data:x(year):	2003	2004	2005	2006	2007
y (yield in tons):	6	13	17	20	24

Then the value of a + b is :

• A. 16
• B. 20.3
• C. 43
• D. 80.3

Answer 1

Answer: (B)

20.3

Answer 2

$a = \frac{\sum y}{n}$

= $\frac{80}{5}=16$

$b = \frac{\sum X.y}{\sum X^2}$

$\frac{43}{10}=4.3$

Therefore, if we combine a and b

$a+b=16+4.3$

$=20.3$

So, the correct option is (B): $20.3$