Finding the Fourth Proportional to 86.50, 129.71 and 43.15

Step by Step Solution

1. Step 1: Write the proportion equation
   86.50 : 129.71 = 43.15 : x
2. Step 2: Convert to fraction form
   86.50/129.71 = 43.15/x
3. Step 3: Cross multiply
   86.50x = 129.71 × 43.15
4. Step 4: Simplify right side
   86.50x = 5,596.88
5. Step 5: Solve for x
   x = 5,596.88/86.50
6. Step 6: Final answer
   x = 64.71