V = π r² h
V = π (4)² 8
V = 402.12
Hope this helps :)
First of all, you need to attach images for this one. Second of all, graph it in desmos and compare. Thirdly, whichever looks like this.
The answer is fairly simple. Each week they sing 8 songs, and so in 5 weeks they would sing 8x5 songs (which is 40) in 6 weeks, they would sing 8x6 songs (which is 48) and in 7 weeks 7x8 songs (which is 56)