12. Incorrect. The answer is
false, not true
Assuming that the emissions of PM-2.5 follow a normal distribution, the inspectors only needs to test the following hypothesis:
H0: β0 = 40
H1 β1 ≠ 40
since they do not know the
true variance of concentrations they approximate it using the observed sample
variance = 2, consequently they use a t statistics:
one tail test
90% confidence interval => 0.99 = 1- a => a = 0.01
T = 18 => d.f. = T-1 =
17
b = sample
mean = 45
sb =
sample standard deviation =
8
P [ -ta/2, n-1 < (b - b0) / (sb/ √T) < ta/2, n-1]
= 99 %
P [ -t0.005, 17 < (45 - 40) /
(8/ √18)
< t0.05, 17] = 99 %
P [ - 2.898
< (45 - 40) / (8/ √18) < 2.898] = 99 %
P [ - 2.898 < 2.6516 < 2.898] = 99 %
=> do not reject the null hyphothesis that the true average concentrations of PM-1.5
is b0 = 40 mg/m3
=> Inspectors cannot conclude that you are
in violation of environmental regulation.