Finding the Third Proportional to 139,212 and 217,140.75

Step by Step Solution

1. Step 1: Write the proportion equation
   139,212 : 217,140.75 = 217,140.75 : x
2. Step 2: Convert to fraction form
   139,212/217,140.75 = 217,140.75/x
3. Step 3: Cross multiply
   139,212x = 217,140.75 × 217,140.75
4. Step 4: Simplify right side
   139,212x = 47,150,105,310.56
5. Step 5: Solve for x
   x = 47,150,105,310.56/139,212
6. Step 6: Final answer
   x = 338,692.82