Finding the Third Proportional to 309,678.50 and 458,760.50

Step by Step Solution

1. Step 1: Write the proportion equation
   309,678.50 : 458,760.50 = 458,760.50 : x
2. Step 2: Convert to fraction form
   309,678.50/458,760.50 = 458,760.50/x
3. Step 3: Cross multiply
   309,678.50x = 458,760.50 × 458,760.50
4. Step 4: Simplify right side
   309,678.50x = 210,461,196,360.25
5. Step 5: Solve for x
   x = 210,461,196,360.25/309,678.50
6. Step 6: Final answer
   x = 679,611.91