. Use the data on education in the table below to answer the questions.

	Mean	Standard deviation	N
Lower class	11.5	2.5	123
Working class	12.7	2.3	697
Middle class	14.1	3.3	683
Upper class	15.6	2.1	38

1. Construct a 90% confidence interval for the mean number of years of education for middle class respondents. Interpret the result.

1. Construct a 90% confidence interval for the mean number of years of education for upper class respondents. Interpret the result.

1. Did middle class respondents differ from upper class respondents in their average number of years of education? Explain your answer.

1. If our sample size for middle class respondents was 200 instead of 683, how would the size of our interval change? You don`t have to calculate it, just explain your answer.

1. If we used the 99% confidence level to construct a confidence interval for middle-class respondents, how would the size of the interval change? You don`t have to calculate it, just explain your answer.