Answer:
D. n1 and n2 can be of different sizes
Step-by-step explanation:
When we are trying to develop interval estimate for difference between two populations, we first select two samples from these populations. We get the interval using the required statistic.
These are:
- Sample size of both populations. Which are n1 and n2 respectively.
- then the Sample mean of two populations
- sample standard deviation.
The samples of different sample sizes can be used and we are not obligated to make use of the same sample size.
Answer:
Part 1)
See Below.
Part 2)

Step-by-step explanation:
Part 1)
The linear approximation <em>L</em> for a function <em>f</em> at the point <em>x</em> = <em>a</em> is given by:

We want to verify that the expression:

Is the linear approximation for the function:

At <em>x</em> = 0.
So, find f'(x). We can use the chain rule:

Simplify. Hence:

Then the slope of the linear approximation at <em>x</em> = 0 will be:

And the value of the function at <em>x</em> = 0 is:

Thus, the linear approximation will be:

Hence verified.
Part B)
We want to determine the values of <em>x</em> for which the linear approximation <em>L</em> is accurate to within 0.1.
In other words:

By definition:

Therefore:

We can solve this by using a graphing calculator. Please refer to the graph shown below.
We can see that the inequality is true (i.e. the graph is between <em>y</em> = 0.1 and <em>y</em> = -0.1) for <em>x</em> values between -0.179 and -0.178 as well as -0.010 and 0.012.
In interval notation:

Thickest to thinnest....
0.33m , 0.3mm, 0.275mm, 0.25mm
Year 2 is 88 million and in year 3 it is 96.8 million. 96.8 million-88 million it makes 8.8 million. So the answer is 8.8 million people.