Finding the Third Proportional to 330,138 and 686,103.75

Step by Step Solution

1. Step 1: Write the proportion equation
   330,138 : 686,103.75 = 686,103.75 : x
2. Step 2: Convert to fraction form
   330,138/686,103.75 = 686,103.75/x
3. Step 3: Cross multiply
   330,138x = 686,103.75 × 686,103.75
4. Step 4: Simplify right side
   330,138x = 470,738,355,764.06
5. Step 5: Solve for x
   x = 470,738,355,764.06/330,138
6. Step 6: Final answer
   x = 1,425,883.59