Finding the Third Proportional to 318,129 and 686,071.50

Step by Step Solution

1. Step 1: Write the proportion equation
   318,129 : 686,071.50 = 686,071.50 : x
2. Step 2: Convert to fraction form
   318,129/686,071.50 = 686,071.50/x
3. Step 3: Cross multiply
   318,129x = 686,071.50 × 686,071.50
4. Step 4: Simplify right side
   318,129x = 470,694,103,112.25
5. Step 5: Solve for x
   x = 470,694,103,112.25/318,129
6. Step 6: Final answer
   x = 1,479,569.93