Answer :
784 marbles shall be distributed in the following order.
X = (3 / 16) X 784 = 147 marbles
Y = (5/ 16) X 784 = 245 marbles
Z = (8/ 16) X 784 = 392 marbles
X = (3 / 16) X 784 = 147 marbles
Y = (5/ 16) X 784 = 245 marbles
Z = (8/ 16) X 784 = 392 marbles
[tex]X:Y:Z=3:5:8=3a:5a:8a\\\\3+5+8=16\\\\a=784:16=49\\\\X=3\times49=147\\Y=5\times49=245\\Z=8\times49=392[/tex]