Finding the Third Proportional to 2,155.78 and 5,208.05

Step by Step Solution

1. Step 1: Write the proportion equation
   2,155.78 : 5,208.05 = 5,208.05 : x
2. Step 2: Convert to fraction form
   2,155.78/5,208.05 = 5,208.05/x
3. Step 3: Cross multiply
   2,155.78x = 5,208.05 × 5,208.05
4. Step 4: Simplify right side
   2,155.78x = 27,123,752.25
5. Step 5: Solve for x
   x = 27,123,752.25/2,155.78
6. Step 6: Final answer
   x = 12,581.87