Acivil engineer is analyzing the compressive strength of concrete. compressive strength is normally distributed with σ = 31.62 psi. a random sample of 36 specimens has a mean compressive strength of 3250 psi. suppose we wish to create a 99% confidence interval with a maximum width of 3 psi. what sample size is required?

A sample size of at least 737 specimens is required.

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 M as such

In which is the standard deviation of the population and n is the size of the sample.

In this problem, we have that:

So:

A sample size of at least 737 specimens is required.

the answer to this question is "motor unit"

x=-2

infinite number of lines, so there is an infinite number of equations.

step-by-step explanation:

there are an infinite number of line that passes through the point (-2,5)

x=-2   is one line that passes through the point

y = 5 is another line that passes through the point

(these two lines are perpendicular to each other).

since the number of   numbers are infinite and the slope is the ratio of two numbers,(change in y over change in x) we can have an infinite number of slopes.     our only condition is that it passes through the point (-2,5)