Finding the Third Proportional to 315,079.50 and 691,390.50

Step by Step Solution

1. Step 1: Write the proportion equation
   315,079.50 : 691,390.50 = 691,390.50 : x
2. Step 2: Convert to fraction form
   315,079.50/691,390.50 = 691,390.50/x
3. Step 3: Cross multiply
   315,079.50x = 691,390.50 × 691,390.50
4. Step 4: Simplify right side
   315,079.50x = 478,020,823,490.25
5. Step 5: Solve for x
   x = 478,020,823,490.25/315,079.50
6. Step 6: Final answer
   x = 1,517,143.53