Firstly, we need to know the price of the TV after the 110$ increase. $165 x 1.10 = $181.50 [This is an increase of $16.50] [1.10 is the equivalent of 110%. 1 being 100% and the .10 being 10%]
Now for the sales tax. We apply a similar method. $181.50 x 0.065 = $11.79 6.5% of $181.50 is $11.79, so we add the two together to find the final cost.
Yes, the confidence interval provides evidence that the average has changed. The prior year’s population mean expenditure per household, $632, is not within the 95% confidence interval, (635, 663).
