Finding the Third Proportional to 139.88 and 208.88

Step by Step Solution

1. Step 1: Write the proportion equation
   139.88 : 208.88 = 208.88 : x
2. Step 2: Convert to fraction form
   139.88/208.88 = 208.88/x
3. Step 3: Cross multiply
   139.88x = 208.88 × 208.88
4. Step 4: Simplify right side
   139.88x = 43,628.77
5. Step 5: Solve for x
   x = 43,628.77/139.88
6. Step 6: Final answer
   x = 311.91