Which THREE systems of linear equations are solved correctly? A)
If x + y = 3 and 2x + y = 12, then x = 9 and y = -6.
If 5x + y = 10 and x + 2y = 8, then x = .
10
B)
4
and y= 3
10
Ž and y=
C)
3
If x + y = 7 and 6x + 2 = 2, then x =
11
2
D)
If 2x + 2y = 4 and x - 4y = 12, then x = 4 and y = -2.
E
If 2x - 4y = 4 and x - 6y = 10, then x = 2 and y = 2.

Acell phone company offers two plans to its subscribers. at the time new subscribers sign up, they are asked to provide some demographic information. the mean yearly income for a sample of 40 subscribers to plan a is $45,000 with a standard deviation of $9,200. for a sample of 25 subscribers to plan b, the mean income is $64,300 with a standard deviation of $7,100. at the 0.025 significance level, is it reasonable to conclude the mean income of those selecting plan b is larger? assume unequal population standard deviations. hint: for the calculations, assume the plan a as the first sample. what is the decision rule? (negative amount should be indicated by a minus sign. round your answer to 3 decimal places.) compute the value of the test statistic. (negative amount should be indicated by a minus sign. round your answer to 2 decimal places.) what is your decision regarding h0 ? reject h0 fail to reject h0 compute the p-value. less than 0.01 between 0.01 and 0.025 between 0.025 and 0.05 between 0.05 and 0.10 greater than 0.10