Finding the Fourth Proportional to 86.10, 128.99 and 34.72

Step by Step Solution

1. Step 1: Write the proportion equation
   86.10 : 128.99 = 34.72 : x
2. Step 2: Convert to fraction form
   86.10/128.99 = 34.72/x
3. Step 3: Cross multiply
   86.10x = 128.99 × 34.72
4. Step 4: Simplify right side
   86.10x = 4,478.30
5. Step 5: Solve for x
   x = 4,478.30/86.10
6. Step 6: Final answer
   x = 52.01