SOLUTION: I am taking an online statistics course and really need help as I have no teacher to talk to. Can you please help me answer these: 1. Consider a population with � = 99.4 and � =

Question 407275: I am taking an online statistics course and really need help as I have no teacher to talk to. Can you please help me answer these:
1. Consider a population with � = 99.4 and � = 5.55 (Points : 6)
(A) Calculate the z-score for x� = 97.3 from a sample of size 38.
(B) Could this z-score be used in calculating probabilities using Table 3 in Appendix B of the text? Why or why not?
4. Assume that the population of heights of female college students is approximately normally distributed with mean  of 64.64 inches and standard deviation  of 6.02 inches. A random sample of 98 heights is obtained. Show all work.
(A) Find the mean and standard error of the x distribution
(B) Find P( -
x > 63.75)

6. A researcher is interested in estimating the noise levels in decibels at area urban hospitals. She wants to be 98% confident that her estimate is correct. If the standard deviation is 5.09, how large a sample is needed to get the desired information to be accurate within 0.57 decibels? Show all work. (Points : 6)

This is the answer I got....is it right?
A = 1 � 0.98 = .02
0.02/2 = 0.01
0.57 - .01 = 0.56 finding the closest on the z table 3 = 5
Z A/2 = 5
E = 0.57 and o = 5.09
N = [(5)(5.09)/0.57]2 = [25.45/0.57]2 = 44.62 = 1989.16
So a sample of 1989 is needed to get the desired info to be accurate within 0.57 decibels

Answer by stanbon(75887) (Show Source): You can put this solution on YOUR website!
1. Consider a population with � = 99.4 and � = 5.55 (Points : 6)
(A) Calculate the z-score for x� = 97.3 from a sample of size 38.
z(97.3) = (97.3-99.4)/[5.55/sqrt(38)] = -2.3325
---------------------------------------------------------
(B) Could this z-score be used in calculating probabilities using Table 3 in Appendix B of the text? Why or why not?
If that Appendix is a z-chart the answer is yes.
If it is a t-chart that could also be used.
---------------------------------------------------
4. Assume that the population of heights of female college students is approximately normally distributed with mean  of 64.64 inches and standard deviation  of 6.02 inches. A random sample of 98 heights is obtained. Show all work.
(A) Find the mean and standard error of the x distribution
Your problem statement gives the mean and std.
Maybe you are looking for the mean and std of the
distribution of sample means which would be
mean of x-bars = 64.64 and std of the x-bars = 6.02/sqrt(98)
===========================================================
(B) Find P(x > 63.75)
z or t of 63.75 = (63.75-64.64)/6.02 = -0.1478
===================
6. A researcher is interested in estimating the noise levels in decibels at area urban hospitals. She wants to be 98% confident that her estimate is correct. If the standard deviation is 5.09, how large a sample is needed to get the desired information to be accurate within 0.57 decibels? Show all work.
---
n = [z*s/E]^2*pq
n = [2.3263*5.09/0.57]^2*(1/2)(1/2)
n = 431.55*(1/4)
n = 107.88
Rounding up you get n = 108
================================
Cheers,
Stan H.
===============

RELATED QUESTIONS
Hello! I need help understanding why (x+y)2 is not equal to x2+y2? I am taking an online... (answered by richard1234,MathLover1)

I'm having trouble figuring out this lesson in my algebra class, I am taking an online... (answered by Alan3354)

Can you please tell me the formula I need to find the solution for this question. "What... (answered by htmentor)

I am taking an algebra class online and I have no idea how to work this problem. Could... (answered by vertciel,Zucchini)

A teacher gives a 20-point test to 10 students. The scores are shown here. Find the value (answered by stanbon)

I'm not sure if this is in the correct section, but I really need help as soon as... (answered by reviewermath)

I am trying to figure out more information on rise and run... I am taking algebra online... (answered by )

Convert the inequality x-y>7 to slope-intercept form. I have no clue what I am doing (answered by stanbon)

Okay can you show we how to solve the equation 3^(2x+1)-10*3^(x)+3=0 Please your help... (answered by stanbon)