Finding the Fourth Proportional to 86.01, 128.98 and 31.15

Step by Step Solution

1. Step 1: Write the proportion equation
   86.01 : 128.98 = 31.15 : x
2. Step 2: Convert to fraction form
   86.01/128.98 = 31.15/x
3. Step 3: Cross multiply
   86.01x = 128.98 × 31.15
4. Step 4: Simplify right side
   86.01x = 4,017.73
5. Step 5: Solve for x
   x = 4,017.73/86.01
6. Step 6: Final answer
   x = 46.71