_20200909_151448ppt

1、Statistics for Managersgroup homeworkSample:1/a.Estimates based on 95% confidence level:Confidence interval of the average monthly cost of living expenses forthe College StudentsA random sample of n = 72 taken from a normal population has X =2.035 and S = 883.Form a 95% confidence interval for S883X

2、 t=2035 (2.0639)a/2, n-1n72b.The confidence interval of the difference between the average monthly living expenses of the male and female studentsmalefemaleb.The confidence interval of the difference between the average monthly living expenses of the male and female students11 )1 and 2 Unknown,(X1 -

3、 X2 ) ta/2+2S(pnn12X1 = 1982, X = 2068= 789859,S2 = 1018083S2- 558 m 38612n1 = 28, n2 = 44= 930053S2pc.A confidence interval of the proportion of students in the whole school15.28%(1 -15.28%)15.28% 1.9611- 0.0598 m 0.3654p Zp(1- p)n2/a.According to the level of a significant=0.05 test, the average m

4、onthly cost of iving expenses is equal to 1500 yuan.a/2=.025a/2=.025 a = 0.050-1.99441.99445.17n = 72o is unknown, so use a t statisticCritical Value:t= 1.994470Reject H0: the average monthly cost of iving expenses is not equal to 1500 yuant= X - = 2035 -1500 = 5.17n-1 S 877n72Reject H0Do not reject

5、 H0Reject H0H0: = 1500 H1: 15002/b.According to the significance of =0.05, whether the average monthly living expenses of the students are significantly different.2068= 1018083a/2=.025= 789859,S2S212a/2=.025n1 = 28, n2 = 44 a = 0.05use a t statistic(X- X)- ( - )Critical Value:t1he9a8v2erage2m0o6nt8h

6、ly cost of iving12t = -0.372So,reject H10.t 71= 1.9939expenses is not equal to 1500 yuan2 1930053 1+ 11Sp 2844 + n1n2(n-1)S 2 + (n-1)S R2eject H(028 -1)S 2Do+no(t4re4jec-t H10 )S 2Reject H0S2 =n =1 72122=-1.993912=1.9939309053p(n-1) + (n-1)(28 -1) + (44 -1) s is u1nknown, s2oX - 2035 -15005.17tn-1 = S= 877= 5.17( n-72)H0: = 1500XH1:=1918520, 0X =1conclusion:H0: 1 - 2 = 0i.e. (1 = 2)H1: 1 - 2 0i.e. (1 2)a = 0.05df = 72-2 = 70Critical Values: t = 1.9944Reject HReject H00-1.994401.9944Test Statistic:t = (1982 - 2068)= -0.37Decision:Reject H0 at a = 0.05 Conclusion:the average monthly living exp