ch 7 practice test Section 7.2 1) - leemath3000.org

1 Ch 7 practice testSection the )Find the critical valuez /2 that corresponds to a degree of confidence of 91%.1)A) ) ) ) ^Express the confidence interval in the form ofp ) < p< )A)^p= )^p= )^p= )^p= the )^The following confidence interval is obtained for a population proportion, p:( , )Use these confidence interval limits to find the point estimate,p .3)A) ) ) ) )The following confidence interval is obtained for a population proportion, < p< these confidence interval limits to find the margin of error, )A) ) ) ) the margin of error for the 95% confidence interval used to estimate the population )In a survey of4100 viewers,20% said they watch network news )A) ) ) ) )In a clinical test with2353 subjects,1136 showed improvement from the )A) ) ) ) ^Find the minimum sample size you should use to assure that your estimate ofp will be within the required margin oferror around the population )^^Margin of ; confidence level:92%;p andq unknown7)A)6327B)1C)40D)63288)^Margin of ; confidence level: 95%.

2 From a prior study,p is estimated by the decimalequivalent of69%.8)A)7396B)14,184C)8218D)26,507 Solve the )464 randomly selected light bulbs were tested in a laboratory,424 lasted more than 500 hours. Finda point estimate of the true proportion of all light bulbs that last more than 500 )A) ) ) ) the given degree of confidence and sample data to construct a confidence interval for the population proportion )A survey of 865 voters in one state reveals that 408 favor approval of an issue before the the 95% confidence interval for the true proportion of all voters in the state who )A) < p< ) < p< ) < p< ) < p< )Of132 adults selected randomly from one town,33 of them smoke. Construct a 99% confidenceinterval for the truepercentage of all adults in the town that )A) < p< ) < p< ) < p< ) < p< the )Find the critical valuez /2 that corresponds to a degree of confidence of 98%.

3 12)A) ) ) ) the confidence level and sample data to find the margin of error )Replacement times for washing machines: 90% confidence;n=36,x= years, = years13)A) yearsB) yearsC) yearsD) years14)College students' annual earnings: 99% confidence;n=71,x= $3660, = $87914)A)$243B)$8C)$269D)$1118 Use the confidence level and sample data to find a confidence interval for estimating the population .15)A random sample of79 light bulbs had a mean life ofx=400 hours with a standard deviation of =28 hours. Construct a 90 percent confidence interval for the mean life, , of all light bulbs of )A)392< <408B)393< <407C)395< <405D)394< <40616)A laboratory tested90 chicken eggs and found that the mean amount of cholesterol was230milligrams with = milligrams.

4 Construct a 95 percent confidence interval for the true meancholesterol content, , of all such )A)227< <233B)226< <232C)228< <234D)226< <233 Use the margin of error, confidence level, and standard deviation to find the minimum sample size required to estimatean unknown population mean .17)Margin of error: $126, confidence level: 99%, = $53417)A)61B)120C)69D)105,268 Section one of the following, as appropriate: (a) Find the critical valuez /2, (b) find the critical valuet /2, (c) state thatneither the normal nor the t distribution )98%; n= 7; = 27; population appears to be normally )A)t /2= )z /2= )t /2= )z /2= )91%; n= 45; is known; population appears to be very )A)t /2= )t /2= )z /2= )z /2= )99%; n= 17; is unknown; population appears to be normally )A)t /2= )t /2= )z /2= )z /2= )90%; n= 10; is unknown; population appears to be normally )A)z /2= )z /2= )t /2= )t /2= )95%; n= 11; is known.

5 Population appears to be very )A)Neither the normal nor the t distribution )z /2= )z /2= )t /2= )90%; n=9; = ; population appears to be very )A)Neither the normal nor the t distribution )z /2= )z /2= )z /2= the margin of )99% confidence interval; n= 201;_x=217; s=3424)A) ) ) ) ) 95% confidence interval; n= 51;_x=388; s=20425)A) ) ) ) the given degree of confidence and sample data to construct a confidence interval for the population mean . Assumethat the population has a normal )A laboratory tested twelve chicken eggs and found that the mean amount of cholesterol was193milligrams with s= milligrams. Construct a 95 percent confidence interval for the true meancholesterol content of all such )A) < < ) < < ) < < ) < < )A savings and loan association needs information concerning the checking account balances of itslocal customers.

6 A random sample of 14 accounts was checked and yielded a mean balance of$ and a standard deviation of $ Find a 98% confidence interval for the true meanchecking account balance for local )A)$ < < $ )$ < < $ )$ < < $ )$ < < $ )The football coach randomly selected ten players and timed how long each player took to performa certain drill. The times (in minutes) were: a 95 percent confidence interval for the mean time for all )A) < < ) < < ) < < ) < < the )Find the critical value 2R corresponding to a sample size of11 and a confidence level )A) ) ) ) the )Find the chi-square value 2L corresponding to a sample size of13 and a confidence level )A) ) ) ) the given degree of confidence and sample data to find a confidence interval for the population standard deviation.

7 Assume that the population has a normal )Weights of men: 90% confidence; n= 14,x= lb, s= lb31)A) lb< < lbB) lb< < lbC) lb< < lbD) lb< < lb32)To find the standard deviation of the diameter of wooden dowels, the manufacturer measures 19randomly selected dowels and finds the standard deviation of the sample to be s= Find the95% confidence interval for the population standard deviation .32)A) < < ) < < ) < < ) < < the appropriate minimum sample )You want to be 95% confident that the sample variance is within30% of the population )A)723B)97C)346D)130 Use the given degree of confidence and sample data to find a confidence interval for the population standard deviation .Assume that the population has a normal )The amounts (in ounces) of juice in eight randomly selected juice bottles a 98 percent confidence interval for the population standard deviation.

8 34)A)( , )B)( , )C)( , )D)( , )Answers:DBADABDCBBBDDCCABBDACAABBDCDBCB BBB4