A Social service agency plans to conduct a survey to determine the mean income of its clients. The director of the agency prefers that you measure the mean income very accurately, to within plus or minus $500. from a sample taken 2 years ago, you estimate that the standard deviation of income for this population is about $5000. I need to figure out the necessary sample size to reduce the confidence interval to plus/minus$500

the necessary sample size to reduce the confidence interval to plus/minus$500 is

Step-by-step explanation:

We are given from the question that

          Marginal error E = $500

        The standard deviation is = $5000

        Let the level of significance be

In order to obtain the sample size n we make use of formula

 Now   is the Z score of /2 and this can be obtained from the z-table and from the z table the  z - score for this case of level of significance  is 1.96

  Substituting value into the formula above

dunno

step-by-step explanation:

if the eqn of the parabola is f(x) = (x-4)(x+2), we need to mult. this out to find the coordinates of the vertex.

then f(x) = x^2 + 2x - 4x - 8, and f(x) = x^2 - 2x - 8.

one way in which you can find the vertex is to calculate x = -b / (2a).   here, that comes to

        )

x = = 1.   f(1) = 1^2 - 2(1) - 8 = - 9.   vertex is at (1, -9).

        2(1) 

find another point on the curve:   let x=0, for which y=-8.   then (0, -8) is on the curve.   plot the vertex and this point and draw a smooth parabola thru both.

hope this