Answer:
7.1 GB
Explanation:
1. Calculate the folder size
The size of an average music file is about 3.5 MB.
2015 files × (3.5 MB/1 file) = 7050 MB
2. Convert to gigabytes
1 GB = 1000 MB
7052 MB × (1 GB/1000 MB) = 7.1 GB
Rosa's folder size is about 7.1 GB.