Question

Question No. 5: [5+2+4+4=15 Marks] A market trader sells mobiles on his stall. He sells the mobiles for a different fixed price, x in number of days. He notes the number of mobiles, y that he sells in each of these days. The results are shown in the following table: x (mobiles) y(days) 3 4 6 5 7 11 15 8 9 17 1) Find the coefficient of correlation and interpret it. 2) Calculate the equation of the regression line of yon x y* = a + bx 3) If he sells 7 mobiles, how many days he will take to sell?

Answer 1

ח A E B с Mobiles (x) Days (Y) 3 5 D X2 E Y? 1 XY 2 25 15 3 4 7 9 16 36 49 28 4 6 11 121 66 5 8 15 64 225 120 6 9 17 81 289 153 7 SUM: 30 55 206 709 382

Rued 5 formula for Coefficient correlation of e is given by e = n (ény) - (én) [Ey) v (n Ex-({4}?) (nɛy - (Ey) ?) putting values 5(382) - (30) (55) (5 (206) – (3012) (5(709)-(55)2) ol - 1910 1650 (1030 - 900) (3545 - 3025) 94 - 260 5 (130) (520) M 260 67600 r = 260 260 i=1 This Means between there is a perfect positive correlation the number Mobiles and of days.

(2) Regression Equation is - at bn y where y N- days Mobiles a = inlexcept b= slope we have to find ai and by which are given by n. Eny - (En) (Ey! n (232) (82)2 putting 5(382) - (30)(55) values b = 5(206) - (30) b 1910 1650 1030 - 900 b 260 130 b 11 and a = sy be •ben valus putting

SS з (30) S a SS - Go a a — ( Тие се regression Equation is a 9* . + 9 x C) we are quen that : given х = value и pu таа е том Equaьзо + 2 (1) - | + (ч 3- - 13 7 Mobiles . to Se 1 13 Therefore It take d°