Q. Maxwell's hot chocolate is concerned about the effect of the recent year-long coffee advertising campaign on the chocolate sales. The average weekly hot chocolate sales two years ago was 884.5 pounds and standard deviation was 72.6 pounds. Maxwell's has randomly selected 19 weeks from the past year and found average sales of 912.5 pounds. (a)State appropriate hypothesis for testing whether hot chocolate sales have decreased. (b)At the 10% significance level, test the hypothesis. (c) Compute the estimated standard error for the mean.