document.write( "<A HREF=/cgi-bin/jump-to-question.mpl?question=407275>Question 407275</A>: <I><SPAN STYLE=\"word-break: break-all;\"> 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:\r<BR>\n" );
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document.write( "1. Consider a population with µ = 99.4 and ð = 5.55 (Points : 6) <BR>\n" );
document.write( "(A) Calculate the z-score for x– = 97.3  from a sample of size 38.<BR>\n" );
document.write( "(B) Could this z-score be used in calculating probabilities using Table 3 in Appendix B of the text?  Why or why not?\r<BR>\n" );
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document.write( "4. Assume that the population of heights of female college students is approximately normally distributed with mean &#61549; of 64.64 inches and standard deviation &#61555; of 6.02 inches. A random sample of 98 heights is obtained.  Show all work.  <BR>\n" );
document.write( "(A)  Find the mean and standard error of the x distribution <BR>\n" );
document.write( "(B)  Find  P( -<BR>\n" );
document.write( "              x > 63.75)\r<BR>\n" );
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document.write( "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)\r<BR>\n" );
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document.write( "This is the answer I got....is it right? \r<BR>\n" );
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document.write( "A = 1 – 0.98 = .02<BR>\n" );
document.write( "0.02/2 = 0.01<BR>\n" );
document.write( "0.57 - .01 = 0.56 finding the closest on the z table 3 = 5<BR>\n" );
document.write( "Z A/2 = 5 <BR>\n" );
document.write( "E = 0.57 and o = 5.09 <BR>\n" );
document.write( "N = [(5)(5.09)/0.57]2 = [25.45/0.57]2 = 44.62 = 1989.16 <BR>\n" );
document.write( "So a sample of 1989 is needed to get the desired info to be accurate within 0.57 decibels\r<BR>\n" );
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document.write( "</I><HR><TABLE width=100%><TR><TD><B><A HREF=http://www.algebra.com/>Algebra.Com's</A> Answer #287138 by </B><A HREF=/tutors/aboutme.mpl?userid=stanbon><B>stanbon(75887)</B></A><img src=\"/images/stars/stars-13.gif\" alt=\"\" >&nbsp;<A HREF=/tutors/aboutme.mpl?userid=stanbon><IMG SRC=http://www.algebra.com/images/aboutme-small.gif BORDER=0 alt=\"About Me\" VALIGN=MIDDLE></A>&nbsp;<IMG SRC=http://www.algebra.com/images/nopicture.jpg><BR>You can <A HREF=\"/cgi-bin/embed-solution.mpl?show=1&solution=287138\">put this solution on YOUR website!</A><BR><SPAN STYLE=\"word-break: break-all;\"> 1. Consider a population with µ = 99.4 and ð = 5.55 (Points : 6) <BR>\n" );
document.write( "(A) Calculate the z-score for x– = 97.3 from a sample of size 38.<BR>\n" );
document.write( "z(97.3) = (97.3-99.4)/[5.55/sqrt(38)] = -2.3325<BR>\n" );
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document.write( "(B) Could this z-score be used in calculating probabilities using Table 3 in Appendix B of the text? Why or why not?<BR>\n" );
document.write( "If that Appendix is a z-chart the answer is yes.<BR>\n" );
document.write( "If it is a t-chart that could also be used.<BR>\n" );
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document.write( "4. Assume that the population of heights of female college students is approximately normally distributed with mean &#61549; of 64.64 inches and standard deviation &#61555; of 6.02 inches. A random sample of 98 heights is obtained. Show all work. <BR>\n" );
document.write( "(A) Find the mean and standard error of the x distribution<BR>\n" );
document.write( "Your problem statement gives the mean and std.<BR>\n" );
document.write( "Maybe you are looking for the mean and std of the <BR>\n" );
document.write( "distribution of sample means which would be<BR>\n" );
document.write( "mean of x-bars = 64.64 and std of the x-bars = 6.02/sqrt(98)<BR>\n" );
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document.write( "(B) Find P(x > 63.75)<BR>\n" );
document.write( "z or t of 63.75 = (63.75-64.64)/6.02 = -0.1478<BR>\n" );
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document.write( "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. <BR>\n" );
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document.write( "n = [z*s/E]^2*pq<BR>\n" );
document.write( "n = [2.3263*5.09/0.57]^2*(1/2)(1/2)<BR>\n" );
document.write( "n = 431.55*(1/4)<BR>\n" );
document.write( "n = 107.88<BR>\n" );
document.write( "Rounding up you get n = 108<BR>\n" );
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document.write( "Cheers,<BR>\n" );
document.write( "Stan H. <BR>\n" );
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