Finding the Fourth Proportional to 139.17, 208.71 and 57.98

Step by Step Solution

1. Step 1: Write the proportion equation
   139.17 : 208.71 = 57.98 : x
2. Step 2: Convert to fraction form
   139.17/208.71 = 57.98/x
3. Step 3: Cross multiply
   139.17x = 208.71 × 57.98
4. Step 4: Simplify right side
   139.17x = 12,101.01
5. Step 5: Solve for x
   x = 12,101.01/139.17
6. Step 6: Final answer
   x = 86.95