Finding the Fourth Proportional to 102.78, 141.88 and 86.38

Step by Step Solution

1. Step 1: Write the proportion equation
   102.78 : 141.88 = 86.38 : x
2. Step 2: Convert to fraction form
   102.78/141.88 = 86.38/x
3. Step 3: Cross multiply
   102.78x = 141.88 × 86.38
4. Step 4: Simplify right side
   102.78x = 12,255.59
5. Step 5: Solve for x
   x = 12,255.59/102.78
6. Step 6: Final answer
   x = 119.24