Finding the Third Proportional to 128,728.75 and 280,342

Step by Step Solution

1. Step 1: Write the proportion equation
   128,728.75 : 280,342 = 280,342 : x
2. Step 2: Convert to fraction form
   128,728.75/280,342 = 280,342/x
3. Step 3: Cross multiply
   128,728.75x = 280,342 × 280,342
4. Step 4: Simplify right side
   128,728.75x = 78,591,636,964
5. Step 5: Solve for x
   x = 78,591,636,964/128,728.75
6. Step 6: Final answer
   x = 610,521.25