Answer:
f'(x) = 
Step-by-step explanation:
i) f(x) = 9 / x
ii) f'(x) = 

Answer:
6,889
<em>Multiply </em>83 x 83.
<h3>
83 x 83 = 6,889.</h3>
Therefore, 83 squared is 6,889.
Answer:
A sample size of 35 is needed.
Step-by-step explanation:
We have that to find our
level, that is the subtraction of 1 by the confidence interval divided by 2. So:

Now, we have to find z in the Ztable as such z has a pvalue of
.
So it is z with a pvalue of
, so 
Now, find the width W as such

In which
is the standard deviation of the population and n is the size of the sample.
How large must the sample size be if the width of the 95% interval for mu is to be 1.0:
We need to find n for which W = 1.
We have that
, then
. So





Rounding up
A sample size of 35 is needed.
Lets say the number is x so we can make an equation
If is at least 21, that means it has to be greater then or equal to it.
6+5*x>=21
You can subtract 6 from both sides
5*x>=15
Then divide both sides by 5
x>=3
You can conclude that the number is greater then or equal to 3.