Finding the Fourth Proportional to 100.76, 139.15 and 86.06

Step by Step Solution

1. Step 1: Write the proportion equation
   100.76 : 139.15 = 86.06 : x
2. Step 2: Convert to fraction form
   100.76/139.15 = 86.06/x
3. Step 3: Cross multiply
   100.76x = 139.15 × 86.06
4. Step 4: Simplify right side
   100.76x = 11,975.25
5. Step 5: Solve for x
   x = 11,975.25/100.76
6. Step 6: Final answer
   x = 118.85