1. I would agree with 5 because a cone is 1/3 of its cylinder and 1/3 of 15 is 5
2. If the diameter is 6, then the radius is 6 ÷ 2 = 3, which also means the height is 3 × 3 = 9. To find the volume, we first need the area of its base circle, and we get this by doing π × radius^2 = π × 3^2 = 9π. Because they want us to use 3.14 as π, you do 9 × 3.14 = 28.26. We figured out the height earlier, so now all you do is 28.26 × 9 = 254.34
I hope this helps!