We want to find the mean of two elements in a set, given that we know the other elements of the set and the mean of the whole set.
The answer is: -490
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For a set with N elements {x₁, x₂, ..., xₙ} the mean is given by:

Here we know that:
- The mean of the set is 0.
- The set has 1000 elements.
- 998 of these elements are ones, the other two are A and B.
We want to find the mean of the values of A and B.
First, we can start by writing the equation for the mean:

We can rewrite this as:

And we have 998 ones, then:

Now we have B isolated.
With this, the mean of A and B can be written as:

So we can conclude that the mean of the other two numbers is -490.
If you want to learn more, you can read:
brainly.com/question/22871228
Answer:
The lower bound for a 90% confidence interval is 0.2033.
Step-by-step explanation:
In a sample with a number n of people surveyed with a probability of a success of
, and a confidence level of
, we have the following confidence interval of proportions.

In which
z is the zscore that has a pvalue of
.
For this problem, we have that:

90% confidence level
So
, z is the value of Z that has a pvalue of
, so
.
The lower limit of this interval is:

The lower bound for a 90% confidence interval is 0.2033.