The answer is 16 inches.
Let r be a radius and h be a height of a cylinder
Since the cylinders are similar, then the ratio between their radiuses is equal to the ratio of their heights:
r1 : r2 = h1 : h2
Cylinder A:
r1 = 5.6 in
h1 = ?
Cylinder B:
r2 = 1.4 in
h2 = 4 in
5.6 : 1.4 = h1 : 4
h1 = 4 * 5.6 : 1.4
h1 = 16 inches
