You'll read numbers from an input file, process them (finding min, max, and average), and write a summary report to an output file. This combines reading and writing in one program.
Writing to files uses ofstream, which works like cout. You open a file for writing, use the << operator to send data to it, and close when done. If the file doesn't exist, it gets created.
If it exists, it gets overwritten by default. This problem teaches the read-process-write pipeline common in data processing. You'll track running statistics while reading, then output a formatted report.
It's a template for many real-world file processing tasks.