**Problem Analysis:**
We are given three equal cubes placed adjacently in a row. Let's assume that the length of each side of the cube is 'a'. We are required to find the ratio of the total surface area of the new cuboid formed to the sum of the surface areas of the three cubes.

**Solution:**
To solve this problem, we will follow these steps:

1. Calculate the surface area of each cube.
2. Calculate the total surface area of the three cubes.
3. Calculate the dimensions of the new cuboid.
4. Calculate the surface area of the new cuboid.
5. Find the ratio of the surface areas.

**Step 1: Calculate the surface area of each cube**
The surface area of a cube is given by 6a^2, where 'a' is the length of each side.
Therefore, the surface area of each cube is 6a^2.

**Step 2: Calculate the total surface area of the three cubes**
Since there are three cubes, the total surface area of the three cubes is 3 times the surface area of each cube.
Total surface area of the three cubes = 3 * 6a^2 = 18a^2.

**Step 3: Calculate the dimensions of the new cuboid**
When three equal cubes are placed adjacently in a row, they form a new cuboid. The length of the cuboid will be three times the length of each cube, i.e., 3a. The width and height of the cuboid will be the same as the length of each cube, i.e., a.

**Step 4: Calculate the surface area of the new cuboid**
The surface area of a cuboid is given by 2lw + 2lh + 2wh, where l, w, and h are the length, width, and height of the cuboid, respectively.
Therefore, the surface area of the new cuboid is 2(3a)(a) + 2(3a)(a) + 2(a)(a) = 18a^2 + 2a^2 + 2a^2 = 22a^2.

**Step 5: Find the ratio of the surface areas**
The required ratio is the surface area of the new cuboid to the total surface area of the three cubes.
Ratio = (surface area of new cuboid) / (total surface area of three cubes) = (22a^2) / (18a^2) = 11/9.

Therefore, the ratio of the total surface area of the new cuboid to the sum of the surface areas of the three cubes is 11/9.

Let side of cube is x
surface area of cube is 6x^2
so 3 cubes will have surface area 18x^2
length of cuboid is 3x breadth is x and length is x
surface area of cuboid is 2 (lb+bh+hl)
2(3x^2+x^2+3x^2)=2 (7x^2)=14x^2
14x^2/18x^2=7/ 9