Answer:
40 marbles.
Explanation:
Given:
Box A can hold 10 marbles.
Box B is double the height of Box A, four times the length of Box A, and half the width of box A.
Question asked:
How many marbles can Box B hold?
Solution:
Let volume of box A =

Let volume of box B =

Now, suppose:
Length of box A =

Breadth =

Height =

So, volume of box A,

As given, Box B is double the height of Box A, four times the length of Box A, and half the width of box A.
So, Length of box B =

Breadth =

Height =

Volume of box B,
=

By dividing volume of box A with volume of box B:

By cross multiplication:

That means volume of box B is 4 times volume of box A;
∵ Box A can hold = 10 marbles
∴ Box B ( 4 times of box A ) can hold =

Therefore, Box B can hold 40 marbles.