Finding the Fourth Proportional to 86.72, 129.92 and 50.72

Step by Step Solution

1. Step 1: Write the proportion equation
   86.72 : 129.92 = 50.72 : x
2. Step 2: Convert to fraction form
   86.72/129.92 = 50.72/x
3. Step 3: Cross multiply
   86.72x = 129.92 × 50.72
4. Step 4: Simplify right side
   86.72x = 6,589.54
5. Step 5: Solve for x
   x = 6,589.54/86.72
6. Step 6: Final answer
   x = 75.99