Changing prices

In an effort to increase demand and grow your sales, you made some pricing changes starting on 2/21/2017. In an effort to draw more people at lunch, you decreased prices by 20% on lunch items (i.e., soup, sandwiches, and chicken stew) but increased prices on drinks by 20% to offset the lower revenue. You also decreased all other prices by 10% in an effort to boost demand.

Now you want to know if it actually boosted sales. You'll start by filtering the data into two groups to perform other analyses.

Just as a reminder, to convert to a date value you can use the function DATE(), which takes the year, month, and day as arguments (e.g., DATE(1969,7,20)).