Question: Suppose the true average income for single head of household families in the US is $51,127 back in 2012. In 2014 a random sample of 130 families from throughout the country and the mean income was determined to be $53,869. Construct a 95% interval estimate for the true mean income of 2014 families if we know the true standard deviation in incomes is 12.5 thousand dollars. Is there evidence to say the incomes have increased from 2012 to 2014? Explain.