document.write( "<A HREF=/cgi-bin/jump-to-question.mpl?question=678723>Question 678723</A>: <I><SPAN STYLE=\"word-break: break-all;\"> <BR>\n" );
document.write( "The head accountant at Raglan resources is concerned over the clerical errors on outgoing invoices and suspects that more than 20% of these invoices contain at least one error. In a random sample of 500 invoices, 120 are found to contain at least one error. Do these data support the account’s views? Let alpha=.05<BR>\n" );
document.write( "2. A random sample of 36 radio stations is selected in order to estimate the average charge for the same fixed-length spot announcement. The sample mean and standard deviation are $20.00 and $8, respectively. Assume that the charge made by all radio stations of the type sampled area approximately normally distributed. Construct the 95% confidence interval for the mean.<BR>\n" );
document.write( "3. A random sample of 64 bearings produced by a machine has a mean diameter of 1.5 inches with a standard deviation of 0.1 inch. Constructs a 90% confidence interval for the mean diameter of ball the bearings?<BR>\n" );
document.write( "4. Students working for a doctorate in education wishes to draw samples of high school freshmen in order to estimate the average amount of time per day they spend studying. A standard deviation of 25 minutes was reported by another researcher conducting a similar study. The students want a 95% level of confidence in calculating the population mean. How large should the sample be if the estimate needs to be within minutes of the true mean?<BR>\n" );
document.write( "5. Suppose it is known that the time spent by customers’ in a fast- food restaurant is a normally distributed variable with a, mean of 16 minutes and a standard deviation of 4 minutes. What is the probability that a random sample of 25 customers will yield a mean between 15 and 18 minutes, inclusive?<BR>\n" );
document.write( "The credit manager of the Adler department store chain believes that average age of his charge-account customers is less than 30 years. A random sample of 100 charge-account customers reveals a mean age of 27 years and a standard deviation of 5 years. Do these data provide sufficient evidence to support the credit manager’s belief? Let alpha=.05<BR>\n" );
document.write( "7. Nothings the declining popularity of public billiard parlors, a recreation specialist hypothesizes that 12% of the homes in a certain area have pool tables. In a random sample of 100 homes in the areas, 16 found to have pool tables. Do these data support the recreation specialist’s contention? Let alpha=.01<BR>\n" );
document.write( "8. A certain type of yarn is manufactured under specifications that the mean tensile strength must be 25 pounds. A random sample of the 16 specimens yields a mean tensile strength of 24 pounds and a sample standard deviation of 3.2 pounds. Can we conclude from these data that mean tensile strength for the population is less than 25 pounds?<BR>\n" );
document.write( "9. In a certain population, 45 percent of the adults go to church regularly. If a random sample of 200 adults is selected from this population, what is the probability that the sample proportion will exceed 0.50?<BR>\n" );
document.write( "10. During a winter shortage of matural gas, citizens are asked to lower the thermostats in their homes to 65 degree or less. A random sample of 300 households in a mid-western town reveals that 225 have  </SPAN>\n" );
document.write( "</I><HR><TABLE width=100%><TR><TD><B><A HREF=http://www.algebra.com/>Algebra.Com's</A> Answer #421592 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=421592\">put this solution on YOUR website!</A><BR><SPAN STYLE=\"word-break: break-all;\"> A used car salesperson estimates the probabilities for the number the number of cars sold in a week as follow- <BR>\n" );
document.write( "number—0, 1, 2 ,3,4,5 <BR>\n" );
document.write( "Probability-.05,.20,.35,.25,.10,.05 <BR>\n" );
document.write( "a) What is the probability for a given week that four or more cars will be sold?<BR>\n" );
document.write( "P(4 or more sold) = P(4 sold) + p(5 sold) = 0.10 + 0.05 = 0.15<BR>\n" );
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document.write( "b) Find the expected number of cars sold in a week <BR>\n" );
document.write( "Multiply each \"number value\" by its corresponding probability.<BR>\n" );
document.write( "Add those 6 products to get the expected number sold<BR>\n" );
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document.write( "c) What is the probability that the salesperson will sell more than 2 cars in a given week?<BR>\n" );
document.write( "P(sell more than 2) = P(3)+P(4)+p(5) = 0.4<BR>\n" );
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document.write( "d) For a period of 3 weeks, what is the probability that salesperson will sell more than 2 cars every week? <BR>\n" );
document.write( "Ans: 0.4^3 = 0.064<BR>\n" );
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document.write( "Cheers,<BR>\n" );
document.write( "Stan H.<BR>\n" );
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