26) A sample of size n - 15 is drawn from an approximately normal population who

Question

26) A sample of size n - 15 is drawn from an approximately normal population whose 26)_ standard deviation iS-55. The sample interval for . is x 40.8. Construct a 90% confidence A) (40.80, 43.14) C) (30.28, 51.32) B) (39.80, 41.80) D) 38.46, 43.14 27 A sample of size n S0 is drawn from.a population whose standard deviation is 27) 14,5, Find the margin of error fora 90% confidence interval A) 3.37 B) 0.80 C) 2.05 D) 0.89 28) A sample of 132 tobacco smokers who recemtly completed a new smoking-cessation 28) program were asked to rate the effectiveness of the program on a scale of 1 to 10, with 10 corresponding to "completely effective" and 1 corresponding to "completely ineffective". The average rating was 5.7 and the standard deviation was 4.7 tc A+8+C+D Construct a 95% confidence interval for the mean score. B) (0, 5.7) C) (4.9,6.5) D) (5.4,6.0) 29) In a survey of 302 registered voters, 167 of them wished to see Mayor Waffleskate lose 29) her next election. Find a point estimate for the proportion of registered voters who wish to see Mayor Waffieskate defeated. A) 167 B) 0.5530 C) 0.02861 D) 0.4470 30) In a survey of 314 registered voters, 156 of them wished to see Mayor Waffleskate lose 30) her next election. Construct a 95% confidence interval for the proportion of registered voter who want to see Mayor Waffleskate defeated. A) (0.441, 0.552) C) 0.450, 0.543) B) (0.388, 0.605) D) (0.469, 0.525) 31)Construc a 95%confidence interval for the population standard deviation ifa sample of size 18 has standard deviationg20) 5s686 31) A) (14.69, 28.74) C) (15.11, 29.58) B) (15.01, 29.98) D) (15.70, 28.00) 32) Find the critical values for a 95% confidence interval using the chi-square distribution 32) with 14 degrees of freedom. A) 5.009, 24.736 C) 6.571, 23.685 B) 5.629, 26.119 D) 5.892, 22.362 2 / A-5 /181

Explanation / Answer

26)

Upper confidence limit = mean + (upper-(0.10/2)percentile * standard deviation / (sqrt(sample size)))

= 40.8 + ( 1.65*5.5 / sqrt(15))

=43.14

Lower confidence limit = mean - (upper-(0.10/2)percentile * standard deviation / (sqrt(sample size)))

= 40.8 - ( 1.65*5.5 / sqrt(15))

= 38.46

Thus conf interval is (38.46, 43.14)

27)

Margin of error for a 90% conf interval is

= upper-(0.10/2)percentile * standard deviation / sqrt(sample size )

= 1.65 * 14.5 /sqrt(50)

~ 3.38

Thus the margin of error is 3.38

28)

Upper confidence limit = mean + (upper-(0.05/2)percentile * standard deviation / (sqrt(sample size)))

= 5.7 + ( 1.96*4.7 / sqrt(132))

=6.5

Lower confidence limit = mean - (upper-(0.05/2)percentile * standard deviation / (sqrt(sample size)))

= 5.7 - ( 1.96*4.7 / sqrt(132))

= 4.9

Thus conf interval is (4.9,6.5)

29)

The point estimate of proportion of voters who wish to see Mayor defeated is

= 167/302

=0.5530

The proportion is 0.5530

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