Finding the Fourth Proportional to 100.76, 139.30 and 86.18

Step by Step Solution

1. Step 1: Write the proportion equation
   100.76 : 139.30 = 86.18 : x
2. Step 2: Convert to fraction form
   100.76/139.30 = 86.18/x
3. Step 3: Cross multiply
   100.76x = 139.30 × 86.18
4. Step 4: Simplify right side
   100.76x = 12,004.87
5. Step 5: Solve for x
   x = 12,004.87/100.76
6. Step 6: Final answer
   x = 119.14