**Explanation:**

To find the eccentricity of an ellipse, we need to know the lengths of the major and minor axes. In this case, we are given that the length of the major axis is three times the length of the minor axis. Let's break down the problem into steps to find the eccentricity.

**Step 1: Identify the given information:**
- Length of major axis = 3 * length of minor axis

**Step 2: Standard equation of an ellipse:**
The standard equation of an ellipse with the center at the origin is given by:
x^2/a^2 + y^2/b^2 = 1

**Step 3: Relation between the lengths of axes and the eccentricity:**
The eccentricity (e) of an ellipse is related to the lengths of the major axis (2a) and the minor axis (2b) by the formula:
e = √(1 - (b^2/a^2))

**Step 4: Determine the lengths of axes:**
Since the length of the major axis is three times the length of the minor axis, we can write:
2a = 3 * 2b
a = (3/2) * b

**Step 5: Substitute the values in the formula for eccentricity:**
Substituting the values of a and b in the formula for eccentricity, we get:
e = √(1 - (b^2/((3/2)^2 * b^2)))
e = √(1 - (4/9))
e = √(5/9)
e = √5/3

Therefore, the eccentricity of the given ellipse is √5/3.

**Summary:**
- Given that the length of the major axis is three times the length of the minor axis.
- Using the standard equation of an ellipse and the formula for eccentricity, we can find that the eccentricity of the ellipse is √5/3.