Finding the Fourth Proportional to 86.69, 129.89 and 83.50

Step by Step Solution

1. Step 1: Write the proportion equation
   86.69 : 129.89 = 83.50 : x
2. Step 2: Convert to fraction form
   86.69/129.89 = 83.50/x
3. Step 3: Cross multiply
   86.69x = 129.89 × 83.50
4. Step 4: Simplify right side
   86.69x = 10,845.82
5. Step 5: Solve for x
   x = 10,845.82/86.69
6. Step 6: Final answer
   x = 125.11