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

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