X Y XY X2
20 82 1640 400
16
70 1120 256
24 90 2160 576
?X = 60 ?Y = 242 ?XY = 4920 ? X2 = 1232
Solution
(i)
N = 3 (Three pairs of data for X and Y)
20002522479000b = (n?XY) – (?X?Y)
(n? X2) – (? X)2
63754035306000= (3 * 4920) – (60 * 242)
(3 * 1232) – (602)
= 240/96
b= 2.5
a= Y- bX
= (242/3) – 2.5(60/3)
= 80.67 – 50
= 30.67
The regression equation:
Y= a + bX, substitute in the equation (a) and (b) as calculated above
Y= 30.67+2.5X
(ii)
Y= 30.67+2.5X
When X = 15, 000 units
Y= 30.67+2.5(15)
= 30.67 + 37.5
= 68.17
= K 68170
