This question was already posted by you and answered.
Edit: If you still don't understand, ask on your previous quesiton thread instead of reposting.
Masses are related by their volumes.
If two solids are similar their volumes are related to their corresponding lengths by their cubes in this way:
If a length of solid A has length "La" and the corresponding length of solid B has length "Lb"
and if the volume of solid A has volume "Va" and the volume of solid B has volume "Vb",
then: Va / Vb = (La)3 / (Lb)3.
Also, for areas (by their squares): Aa / Ab = (La)2 / (Lb)2
Let's use this area relationship to find the lengths and then use these lengths to find the volumes.
Aa / Ab = (La)2 / (Lb)2 ---> 40.32 / 28 = (La)2 / (Lb)2 ---> sqrt(40.32) / sqrt(28) = La / Lb
Now, let's use the volume formula ---> Va / Vb = (La)3 / (Lb)3 ---> Va / Vb = [ sqrt(40.32) ]3 / [ sqrt(28) ]3
Va = [ sqrt(40.32) ]3 = 256.024 Vb = [ sqrt(28) ]3 = 148.162
We can now use these values for the volumes to find the mass of A:
mass(A) / mass(B) = Va / Vb ---> mass(A) / 6912 = 256.024 / 148.162
---> mass(A) = 11944 grams
Make sure you're learning from this and not just looking for the answers!!
Check the answer given at : https://web2.0calc.com/questions/math-problem_67#r1 where you first asked it. Don't repeat a question without checking the original!
NB Geno made a slight mistake by inverting the ratio on the RHS.
But if A is smaller then B and they are made from the same material, how is the answer 11943.94?