Answer:
See Explanation
Step-by-step explanation:
I will answer this question with the attached square pyramid
From the attached pyramid, we have:

So, the base area is:



The dimension of each of the 4 triangles is:


So, the area of 4 triangles is:



So, the surface area is:



total no of marbles = 10
no of marbles which are not white = 8
8/10 = 4/5
hope it helps...!!!