Finding the Fourth Proportional to 101.39, 139.69 and 86.61

Step by Step Solution

1. Step 1: Write the proportion equation
   101.39 : 139.69 = 86.61 : x
2. Step 2: Convert to fraction form
   101.39/139.69 = 86.61/x
3. Step 3: Cross multiply
   101.39x = 139.69 × 86.61
4. Step 4: Simplify right side
   101.39x = 12,098.55
5. Step 5: Solve for x
   x = 12,098.55/101.39
6. Step 6: Final answer
   x = 119.33