Answer:
A)
Note that
Lower Bound = X - z(alpha/2) * s / sqrt(n)
Upper Bound = X + z(alpha/2) * s / sqrt(n)
where
alpha/2 = (1 - confidence level)/2 = 0.025
X = sample mean = 1723.4
z(alpha/2) = critical z for the confidence interval = 1.959963985
s = sample standard deviation = 89.55083319
n = sample size = 30
Thus,
Lower bound = 1691.355235
Upper bound = 1755.444765
Thus, the confidence interval is
( 1691.355235 , 1755.444765 ) [ANSWER]
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b)
We assumed taht the distirbution of these observations is approximately normally distributed.
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c)
Yes, because the values are not far away from each other.
<span>The method of solving "by substitution" works by solving one of the equations (you choose which one) for one of the variables (you choose which one), and then plugging this back into the other equation, "substituting" for the chosen variable and solving for the other. Then you back-solve for the first variable.</span>
Answer:
B.
Step-by-step explanation:
I believe the answer is 6x-7y=-11