Suppose a sample of 200 local vendors is selected as part of a survey conducted by the Ministry of Trade and it is found that 145 of the local vendors make an average income in excess of $ 7 600 per month.
1. What is the 98% confidence interval estimate of the population proportion of local vendors who make an average income in excess of $ 7 600 per month?
2. Suppose that a 97% confidence interval estimate of the proportion of local vendors who make an average income less than $ 7 600 per month is required. How large a sample should be taken if the desired margin of error is 5%?
3. Suppose it has been established from past studies that 75% of local vendors make an average income in excess of $ 7 600 per month. Use the p-value approach and conduct a hypothesis test at a 1% level of significance to determine whether the proportion of local vendors who make an average income in excess of $ 7 600 per month differs from the historical level. Show all hypothesis test steps.
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