Question

Please answer all

Question 36 1 pts A shipping firm suspects that the mean lifetime of the tires used by its trucks is less than 35,000 miles. To check the claim, the firm randomly selects and tests 54 of these tires and gets a mean lifetime of 34,570 miles with a standard deviation of 1200 miles. At a = 0.05, test the shipping firm's claim. test statistic -2.63; critical value = -1.645; do not reject Ho: There is sufficient evidence to support the shipping firm's claim. test statistic -2.63; critical value = -1.960; reject Ho: There is sufficient evidence to support the shipping firm's claim. test statistics -2.63; critical value = -1.960; do not reject Ho: There is not sufficient evidence to support the shipping firm's claim. O test statistic = -2.63; critical value = -1.645; do not reject Ho. There is not sufficient evidence to support the shipping firm's claim. O test statistic -2.63; critical value = -1.645: reject Ho; There is sufficient evidence to support the shipping firm's claim. O None of these

Answer 1

34)

sample mean 'x̄=		2.300
sample size    n=		45
std deviation σ=		0.23
std error ='σx=σ/√n=0.23/√45=		0.034

for 90 % CI value of z=		1.645	from excel:normsinv((1+0.9)/2)
margin of error E=z*std error =		0.0564
lower bound=sample mean-E=		2.24
Upper bound=sample mean+E=		2.36

Correct option is : 2.24 to 2.36 minutes

35)

[16.3, 17.9); It doesn't contradict the claim, since 17.8 is inside the interval.

36_)

population mean μ=		35000
sample mean 'x̄=		34570.000
sample size    n=		54
std deviation σ=		1200.00
std error ='σx=σ/√n=1200/√54=		163.299
z statistic= ='(x̄-μ)/σx=(34570-35000)/163.299=		-2.63

O test statistic -2.63; critical value = - 1.645; reject Ho: There is sufficient evidence to support the shipping firm's claim.