Since we are dealing with a volume problem (3 dimensions) when you increase the radius by a factor of 2, you increase the volume by a factor of 2^3 or 8 So, the larger sphere has a volume 8 times greater than the smaller sphere.
Answer : No, the new type of letter wouldn't be considered as a success because its response rate (2.71%) is lower than the average response rate which is 4%.
