document.write( "<A HREF=/cgi-bin/jump-to-question.mpl?question=138129>Question 138129</A>: <I><SPAN STYLE=\"word-break: break-all;\">  Please, Please, Please can someone help me with these questions?? I am just totally confused. This is due tommorrow and I have no idea what i am doing. I would appreciate any and all help with these. <BR>\n" );
document.write( "1) A pooled estimate of the variance is a weighted average of the variance using the two sample variances and the ___________ of each variance as the weights. <BR>\n" );
document.write( "2) If a baseball player's batting average is 0.340 or 34%, find the probability that the player will have a bad season and only score at most 60 hits in the 200 times at bat?<BR>\n" );
document.write( "A) 12.64%<BR>\n" );
document.write( "B) 11.72%<BR>\n" );
document.write( "C) 50.34%<BR>\n" );
document.write( "D) 13.14% <BR>\n" );
document.write( "3) When the subjects are paired or matched in some way, samples are considered to be____________? <BR>\n" );
document.write( "4) What y z value corresponds to the 17% of the data between the mean and the z value?<BR>\n" );
document.write( "A) 1.25<BR>\n" );
document.write( "B) 0.44<BR>\n" );
document.write( "C) 0.52<BR>\n" );
document.write( "D) 2.10 <BR>\n" );
document.write( "5) A sample of 400 racing cars showed that 80 cars cost over $700,000. What is the 99% condidence interval of the true proportion of cars costing over $700,000? \r<BR>\n" );
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document.write( "6) Find the probability for P(0 A) 0.4525 or 45.25%<BR>\n" );
document.write( "B) 0.4554 or 45.54%<BR>\n" );
document.write( "C) 0.4207 or 42.07%<BR>\n" );
document.write( "D) 0.3554 or 35.54% <BR>\n" );
document.write( "7) Dr. Christina Cuttleman, a nutritionist, claims that the average number of calories in a serving of popcorn is 75 with a standard deviation of 7? A sample of 50 servings of popcorn yields an average of 78 calories. Check Dr. Cuttleman's claim at a=0.05. \r<BR>\n" );
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document.write( "8) The Eagle Ridge Contractors Association claims the average price of a home in thier subdivision is $125,150 with a standard deviation of $ 7,350. A sample of 36 homes for sale in this subdivision had an average selling price of $123,550. Is there evidence that the costs of homes for sale in this subdivision are actually lower than claimed? Test a=0.05, what is the test value?<BR>\n" );
document.write( "A) -1.31<BR>\n" );
document.write( "B) 1.31<BR>\n" );
document.write( "C) -1.52<BR>\n" );
document.write( "D) 1.52 \r<BR>\n" );
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document.write( "9) Joan moves into her apartment and wants to purchase a new couch. She wants to determine if there is any difference between the average cost of couches at two different stores. Test the hypothesis that there is no difference at a=0.05 <BR>\n" );
document.write( "Store 1 Store 2\r<BR>\n" );
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document.write( "x(sample mean) $650 $730<BR>\n" );
document.write( "o(sample deviation) $61 $ 78<BR>\n" );
document.write( "n 24 21<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 #100884 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=100884\">put this solution on YOUR website!</A><BR><SPAN STYLE=\"word-break: break-all;\"> 1) A pooled estimate of the variance is a weighted average of the variance using the two sample variances and the sum of the sample sizes of each variance as the weights.<BR>\n" );
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document.write( "2) If a baseball player's batting average is 0.340 or 34%, find the probability that the player will have a bad season and only score at most 60 hits in the 200 times at bat?<BR>\n" );
document.write( "Its binomial with n=200,p=0.34,0<x<=60<BR>\n" );
document.write( "Use binomcdf(200,0.34,60) if you have a TI calculator<BR>\n" );
document.write( "Ans: 13.14%<BR>\n" );
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document.write( "A) 12.64%<BR>\n" );
document.write( "B) 11.72%<BR>\n" );
document.write( "C) 50.34%<BR>\n" );
document.write( "D) 13.14% <BR>\n" );
document.write( "--------------------<BR>\n" );
document.write( "3) When the subjects are paired or matched in some way, samples are considered to be dependent.<BR>\n" );
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document.write( "4) What y z value corresponds to the 17% of the data between the mean and the z value?<BR>\n" );
document.write( "P(0 < z < ?) = 0.17 ; ? = InvNorm(0.67) = 0.44<BR>\n" );
document.write( "A) 1.25<BR>\n" );
document.write( "B) 0.44<BR>\n" );
document.write( "C) 0.52<BR>\n" );
document.write( "D) 2.10 <BR>\n" );
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document.write( "5) A sample of 400 racing cars showed that 80 cars cost over $700,000. What is the 99% condidence interval of the true proportion of cars costing over $700,000? <BR>\n" );
document.write( "p-hat = 80/400 = 1/5 = 0.2<BR>\n" );
document.write( "E = 2.58*sqrt[0.2*0.8/400] = 0.0516<BR>\n" );
document.write( "99% CI: 0.2-0.0516 < p < 0.2 + 0.0516<BR>\n" );
document.write( "99% CI: 0.1484 < p < 0.2516<BR>\n" );
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document.write( "6) Find the probability for P(0)<BR>\n" );
document.write( "Comment: what do you mean by P(0)? <BR>\n" );
document.write( "A)= 0.4525 or 45.25%<BR>\n" );
document.write( "B) 0.4554 or 45.54%<BR>\n" );
document.write( "C) 0.4207 or 42.07%<BR>\n" );
document.write( "D) 0.3554 or 35.54% <BR>\n" );
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document.write( "7) Dr. Christina Cuttleman, a nutritionist, claims that the average number of calories in a serving of popcorn is 75 with a standard deviation of 7? A sample of 50 servings of popcorn yields an average of 78 calories. Check Dr. Cuttleman's claim at a=0.05.<BR>\n" );
document.write( "Ho: u = 75<BR>\n" );
document.write( "Ha: u is not 75<BR>\n" );
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document.write( "x-bar = 78<BR>\n" );
document.write( "Critical value for alpha = 5% on a two-tail T-test with df=49 is +/-1.96<BR>\n" );
document.write( "Test statistic: t(78) = (78-75)/[7/sqrt(50)] = 3.0304...<BR>\n" );
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document.write( "Conclusion: Since the test statistic is in the reject interval, Reject Ho.<BR>\n" );
document.write( "The mean is not 75\r<BR>\n" );
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document.write( " <BR>\n" );
document.write( "8) The Eagle Ridge Contractors Association claims the average price of a home in their subdivision is $125,150 with a standard deviation of $ 7,350. A sample of 36 homes for sale in this subdivision had an average selling price of $123,550. Is there evidence that the costs of homes for sale in this subdivision are actually lower than claimed? Test a=0.05, what is the test value?<BR>\n" );
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document.write( "t(123,550) = (123550-125150)/[7350/sqrt(36)] = -1.31\r<BR>\n" );
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document.write( "A) -1.31<BR>\n" );
document.write( "B) 1.31<BR>\n" );
document.write( "C) -1.52<BR>\n" );
document.write( "D) 1.52 <BR>\n" );
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document.write( "9) Joan moves into her apartment and wants to purchase a new couch. She wants to determine if there is any difference between the average cost of couches at two different stores. Test the hypothesis that there is no difference at a=0.05 <BR>\n" );
document.write( "......................Store 1 Store 2 <BR>\n" );
document.write( "x(sample mean).........$650... $730<BR>\n" );
document.write( "o(sample deviation).... $61... $78<BR>\n" );
document.write( "n....................... 24.... 21<BR>\n" );
document.write( "Ho: u1-u2 = 0<BR>\n" );
document.write( "Ha: u1-u2 is not 0<BR>\n" );
document.write( "----------------------<BR>\n" );
document.write( "I ran a 2-Sample T-test with pooled samples to get:<BR>\n" );
document.write( "test-statistic = -3.8563...<BR>\n" );
document.write( "p-value = 0.00038...<BR>\n" );
document.write( "df = 43<BR>\n" );
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document.write( "Conclusion:Since p-value is less than alpha=5%, Reject Ho.<BR>\n" );
document.write( "There is ia difference in the average cost of couches at these two stores.<BR>\n" );
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document.write( "Cheers,<BR>\n" );
document.write( "Stan H.\r<BR>\n" );
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