Finding the Third Proportional to 315,080.50 and 691,392.50

Step by Step Solution

1. Step 1: Write the proportion equation
   315,080.50 : 691,392.50 = 691,392.50 : x
2. Step 2: Convert to fraction form
   315,080.50/691,392.50 = 691,392.50/x
3. Step 3: Cross multiply
   315,080.50x = 691,392.50 × 691,392.50
4. Step 4: Simplify right side
   315,080.50x = 478,023,589,056.25
5. Step 5: Solve for x
   x = 478,023,589,056.25/315,080.50
6. Step 6: Final answer
   x = 1,517,147.49