Apoll used a sample of 100 randomly selected car owners. within the sample, the mean time of ownership for a single car was 5.89 years with a standard deviation of 3.26 years. test the claim by the owner of a large dealership that the mean time of ownership for all cars is less than 6.5 years. use a 0.05 significance level.

We reject the null hypothesis at the significance level of 0.05.

Step-by-step explanation:

vs (lower-tail alternative)

We have , and n = 100. We have a large sample and our test statistic is

which is normal standard approximately. We have observed

.

We should use the significance level . The 5th quantile of the standard normal distribution is and the rejection region is given by RR = {z | z < -1.6449}. Because the observed value -1.8712 is less than -1.6449, we reject the null hypothesis at the significance level of 0.05.

the perimeter is increased by a factor of 2

x = -3

y = -18

step-by-step explanation:

to solve by substitution, substitute one variable and solve for the other. then substitute again to find the remaining variable.

x-1/3(3x-9) = -3 since y=3x-9 substittute y.

x-1/3(3x-9)=-3

x + x +3 = -3

2x+3=-3

2x+3-3= -3-3

2x=-6

x=-3

substitute again into y=3x-9

y=3(-3)-9

y=-9-9

y=-18