Finding the Fourth Proportional to 139.01, 208.56 and 57.86

Step by Step Solution

1. Step 1: Write the proportion equation
   139.01 : 208.56 = 57.86 : x
2. Step 2: Convert to fraction form
   139.01/208.56 = 57.86/x
3. Step 3: Cross multiply
   139.01x = 208.56 × 57.86
4. Step 4: Simplify right side
   139.01x = 12,067.28
5. Step 5: Solve for x
   x = 12,067.28/139.01
6. Step 6: Final answer
   x = 86.81