Answer:
Step-by-step explanation:
We are given zeros as x=-4, x=-2
so, we can set up function as
Vertex is at (-1,3)
It means that graph passes through point (-1,3)
so, we can plug x=-1 and f(x)=3
and then we can solve for 'a'
we get
now, we can plug it back
and we get
now, we can simplify it
Answer:
(0.4958, 0.7422)
Step-by-step explanation:
Let p be the true proportion of water specimens that contain detectable levels of lead. The point estimate for p is . The estimated standard deviation is given by
. Because we have a large sample, the 90% confidence interval for p is given by
where
is the value that satisfies that above this and under the standard normal density there is an area of 0.05. So, the confidence interval is
, i.e., (0.4958, 0.7422).