Finding the Third Proportional to 489,311.50 and 689,061.50

Step by Step Solution

1. Step 1: Write the proportion equation
   489,311.50 : 689,061.50 = 689,061.50 : x
2. Step 2: Convert to fraction form
   489,311.50/689,061.50 = 689,061.50/x
3. Step 3: Cross multiply
   489,311.50x = 689,061.50 × 689,061.50
4. Step 4: Simplify right side
   489,311.50x = 474,805,750,782.25
5. Step 5: Solve for x
   x = 474,805,750,782.25/489,311.50
6. Step 6: Final answer
   x = 970,354.78