The fourth proportional of 18, 27, 68 is:

Options

A. 136
B. 170
C. 204
D. 102

Answer

To find the fourth proportional of the numbers 18, 27, and 68, we can use the property of proportions. The fourth proportional \( D \) can be found using the formula:

\[ \frac{A}{B} = \frac{C}{D} \]

Where:
- \( A = 18 \)
- \( B = 27 \)
- \( C = 68 \)
- \( D \) is what we need to find.

### Step-by-Step Solution:

1. **Set up the proportion**:
\[ \frac{18}{27} = \frac{68}{D} \]

2. **Cross-multiply**:
\[ 18 \cdot D = 27 \cdot 68 \]

3. **Calculate \( 27 \cdot 68 \)**:
- First, calculate \( 27 \cdot 68 \):
\[ 27 \cdot 68 = 1836 \]

4. **Substitute back into the equation**:
\[ 18D = 1836 \]

5. **Solve for \( D \)**:
\[ D = \frac{1836}{18} \]

6. **Calculate \( \frac{1836}{18} \)**:
- Divide \( 1836 \) by \( 18 \):
\[ D = 102 \]

Thus, the fourth proportional of 18, 27, and 68 is \( \boxed{102} \).