ktl de2

BM01a/QT01/KT Cu 1: (7 im)

Cho bng s liu v lng sn phm bn c, gi bn sn phm v yu t khuyn mi ca

mt cng ty nh sau:

Y

8.2 8 8 7.9 7.8 7.6 7.5 7.7 7.4 7.6

X 3 3.2 3.4 3.5 3.6 3.8 3.9 4 4.2 4.5

Z

1 0 1 1 0 0 0 1 0 1

Trong :

- Y l lng sn phm bn c (triu sn phm/thng) - X l gi bn mt sn phm (chc ngn ng/sn phm) - Z=1: thng c khuyn mi v Z=0: thng khng c khuyn mi.

a. Vit hm hi qui mu ii

XY21

v cho bit ngha kinh t ca h s gc hi quy c. (2)

b. Tm h s xc nh v cho bit ngha ca n. (1)

c. Tm khong tin cy 99% cho h s gc 2. (1)

d. Mt nghin cu trong nm trc cho thy khi gi bn tng thm 10 ngn ng/sn phm th lng sn phm bn c trung bnh gim xung 800.000 sn phm/thng. Vi mc

ngha 1%, bn hy cho bit tnh hnh nm nay c thay i hay khng? (1)

e. Tm khong tin cy 99% cho lng sn phm bn c trung bnh khi gi bn ca mt sn phm l 37 ngn ng/sn phm? (1)

f. Vit hm hi quy mi vi n v ca Y l ngn sn phm/thng v n v ca X l ngn ng/sn phm? (1)

Cu 2 : (3 im) xc nh tc ng ca khuyn mi ln lng sn phm bn c, ta tin hnh chy m

hnh hi quy bi v thu c kt qu sau : 2

i ii . 0. 0 X 0. Z ; R 0.Y 9 419768 47 526. 191768. 932273

Se = (0.206175) (0.054393) (0.047531) 2R ? a. Vi mc ngha 5%, hy cho bit m hnh cu 2 c ph hp khng? Tnh h s xc

nh hiu chnh ca m hnh cu 2. C th ni m hnh cu 2 ph hp vi mu d

liu hn m hnh cu 1 khng? (1.5)

b. Nu ngha ca h s gc hi quy c ca bin Z. (0.5) c. Cho bit vi cng iu kin v khuyn mi, nu gi bn tng ln 10 ngn ng/sn

phm th lng sn phm bn c trung bnh thay i th no, vi tin cy l

98%?(1)

Cho cc gi tr : 0.005 0.01 0.05t (8) 3.355 ; t (7) 2.998 ; F (2;7) 4.74 Ch : - Cn b coi thi khng c gii thch g thm.