Answer:
We conclude that the mean nicotine content is less than 31.7 milligrams for this brand of cigarette.
Step-by-step explanation:
We are given the following in the question:
Population mean, μ = 31.7 milligrams
Sample mean,
= 28.5 milligrams
Sample size, n = 9
Alpha, α = 0.05
Sample standard deviation, s = 2.8 milligrams
First, we design the null and the alternate hypothesis

We use One-tailed t test to perform this hypothesis.
Formula:

Putting all the values, we have

Now,
Since,
We fail to accept the null hypothesis and accept the alternate hypothesis. We conclude that the mean nicotine content is less than 31.7 milligrams for this brand of cigarette.
Answer:
your answer would be
B complexity
I agree that it is B but would suggest that you also consider the implications of each answer. They are all technically correct.
A is correct simply due to the fact that the longer time passes without an ebola cure, the more people can be potentially infected with it, resulting in less healthy individuals that may be able to volunteer to test potential ebola vaccines. Scientists need healthy volunteers from affected regions in order for rapid clinical trials to occur.
B is correct because of the nature of epidemics. A combination of technical, social, economic, and geographical obstacles slow the progress and dissemination of ebola vaccine information.
C is correct because finance impacts everything from finding resources used in studying ebola to distributing vaccines to affected areas. Economic imbalances or money shortages negatively impact research.
D is correct due to many social factors (more of a subjective answer). Some people think that vaccine distributors discriminate against certain ethnic groups. Others think the governments/other organizations are not effective enough at managing the situation. Still others feel that the search for a cure is not being approached in the right way. In all, there are multiple ways to oppose different aspects of ebola research.
Ultimately, B is correct because it seems to capture the meaning of A, C, and D together.
Looks like a badly encoded/decoded symbol. It's supposed to be a minus sign, so you're asked to find the expectation of 2<em>X </em>² - <em>Y</em>.
If you don't know how <em>X</em> or <em>Y</em> are distributed, but you know E[<em>X</em> ²] and E[<em>Y</em>], then it's as simple as distributing the expectation over the sum:
E[2<em>X </em>² - <em>Y</em>] = 2 E[<em>X </em>²] - E[<em>Y</em>]
Or, if you're given the expectation and variance of <em>X</em>, you have
Var[<em>X</em>] = E[<em>X</em> ²] - E[<em>X</em>]²
→ E[2<em>X </em>² - <em>Y</em>] = 2 (Var[<em>X</em>] + E[<em>X</em>]²) - E[<em>Y</em>]
Otherwise, you may be given the density function, or joint density, in which case you can determine the expectations by computing an integral or sum.