IMPORTANT NOTE!!
The red figures in the excel data file are the sales figures for the respective months of that quarter which will help you achieve the approximate answer to the question mark next to that based on forecast.
For the balance question marks in the file where no info is given, please use any suitable prediction or forecasting method to get the figure.
A sample forecasting technique to predict the question mark figure will be the average of the last 3 months. However, please feel free to use any forecasting method of your choice to get the figure based on suitable logic and research.
All the best!