Can you show me the detailed working for the frustum formulas, specifically for question 7 which has inconsistent dimensions?

As we discussed, your previous solutions were all correct. The challenge with question 7 is that the dimensions provided (heights and radii for both the large and small cones) are inconsistent with a perfect frustum cut from a single cone where the apex Z is common to both. This means the cones are not geometrically similar.

However, your approach of calculating the volume and curved surface area by subtracting the smaller cone's values from the larger cone's values, using the exact dimensions given in the problem, is the most appropriate way to solve it given the inconsistency. This is what you did, and it yielded the correct results.

If we were to strictly