Finding the Third Proportional to 311,978.25 and 638,741.25

Step by Step Solution

1. Step 1: Write the proportion equation
   311,978.25 : 638,741.25 = 638,741.25 : x
2. Step 2: Convert to fraction form
   311,978.25/638,741.25 = 638,741.25/x
3. Step 3: Cross multiply
   311,978.25x = 638,741.25 × 638,741.25
4. Step 4: Simplify right side
   311,978.25x = 407,990,384,451.56
5. Step 5: Solve for x
   x = 407,990,384,451.56/311,978.25
6. Step 6: Final answer
   x = 1,307,752.65