If you make a glass in the shape of a right circular cone (think martini glass) how wide would the glass be if it is 4 inches tall and again holds 12 oz.

Does not specify what the 12 oz are

Figure 12 fluid ouncces, which is 12*1.804 in^3

Volumecone= 1/3 areabase*height
12*1.803 in^3=1/3 PI *(diameter/2)^2*4

solve all this for diameter