QUESTION IN IMAGE!!
2 answers:
You might be interested in
Answer:
a) 21%
b) 45.5%
c) 26.4%
Step-by-step explanation:
Given the supplied information, a table of probabilities can be constructed. (See the attachment.) The numbers across the bottom reflect the given ratios of customers selecting the different gas types. The numbers in the cells are those bottom numbers multiplied by the percentage that fill the tank (or not). The numbers on the right are the sums of the numbers in each row.
a) The top center cell in the table answers this question. It it the product ...
p(plus)×p(fill | plus) = 0.35×0.60 = 0.21 = 21%
__
b) The sum on the right answers this question:
p(fill) = 45.5%
__
c) The ratio of the first column number (12%) to the row sum for Fill (45.5%) answers this question:
p(regular | fill) = 12%/45.5% ≈ 26.4%
The confidence interval is given by
where
is the sample mean and 
is the standard error of the mean. In turn, the standard error of the mean is 
where 
is sample size.
We have
The endpoints of the confidence interval correspond to the finite endpoints of the rejection region. That is,
for which we can solve for
. We get
which is the critical value for a confidence level of
.
where
We have
The endpoints of the confidence interval correspond to the finite endpoints of the rejection region. That is,
for which we can solve for
which is the critical value for a confidence level of