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Hello everyone.
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In this question, it is given that in a survey of 160 canadian adults, 770 say that the energy situation in canada is very or fairly serious.
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Hence, in question one, we need to find the point estimate for the population proportion.
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In question two, we need to construct a 95 percentage confidence interval for the population proportion.
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Therefore, we need to calculate a, the critical value, b, the margin of error, c, the lower limit of the interval and d, the upper limit of the interval.
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In question 3, we need to find the minimum sample size needed to estimate the population proportion at the 99 % confidence level in order to ensure that the estimate is accurate within 5 % of the population proportion.
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Therefore, again we need to calculate a, the critical value, b, the margin of error, and c, the sample size.
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Now recall that the point estimate of the population proportion is the sample proportion, where the sample proportion for any event a is given as p subscript a and this is equal to the number of samples for which a is true.
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That is for which the event a occurs divided by the sample size n now for a hundred multiplied by one minus alpha percentage confidence interval which in short is denoted by c i for the population proportion p where alpha is the significance level it is given as follows here the lower limit of the confidence interval is given by p minus c subscript alpha divided by 2 multiplied by the square root of p multiplied by 1 minus p divided by n and the upper limit of the confidence interval is given by p plus c subscript alpha divided by 2 multiplied by the square root of p multiplied by 1 minus b divided by n n is the sample size.
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Here, c subscript alpha divided by 2 is the critical value at the significance level alpha.
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It is also denoted as the c score and can be obtained from the standard normal distribution table.
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Now the margin of error, in short, denoted by m e, is equal to c subscript alpha divided by 2 multiplied by the square root of p multiplied by 1 minus p divided by n.
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In terms of the margin of error, therefore, the lower limit of the confidence interval can be written as p minus m e and the upper limit of the confidence interval can be written as p plus m e.
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Now in question 1, since it is given that among 160 canadian adults, 7, 7 ,000 ,000, 70 say that the energy situation in canada is very or fairly serious.
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Therefore the sample size n is equal to one zero six zero and hence the point estimate for the population proportion this will be denoted as small p and this is equal to the sample proportion which is equal to 770 divided by one zero 60 and this is approximately equal to 0 .726 therefore this is the answer to question one now in question two a we need to construct a 95 percentage confidence interval for this population proportion.
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So, for a 95 percentage confidence interval, first let us obtain the significance level and we can do this by equating hundred multiplied by 1 minus alpha equal to 95.
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Or from here we obtain alpha is equal to 0 .05 or alpha divided by 2 this is equal to 0 .025.
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Therefore, the critical value at the significance level alpha is equal to 0 .05, this is equal to c subscript alpha divided by 2 and in our problem this is equal to c subscript 0 .025.
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So the c score at the value 0 .025 can be obtained from the standard normal distribution table and this gives us the value 1 .96.
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Therefore this is the answer to question 2a.
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Now in question 2b, we need to find the margin of error.
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Recall the margin of error m .e is given by the formula c subscript alpha divided by 2 multiplied by the square root of e multiplied by 1 minus b divided by n.
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Substituting the values of c -subscript alpha divided by 2 as 1 .96, the population proportion as 0 .726, and the sample size in as 1 .60, we obtain the marginal error as 1 .96 multiplied by the square root of 0 .726 multiplied by the square root of 0 .726 multiplied by.
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1 minus 0 .726 that is 0 .274 divided by 1060.
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If we do this calculation we shall obtain the marginal error as approximately 0 .0269...