Finding the Third Proportional to 2,179.50 and 5,139.75

Step by Step Solution

1. Step 1: Write the proportion equation
   2,179.50 : 5,139.75 = 5,139.75 : x
2. Step 2: Convert to fraction form
   2,179.50/5,139.75 = 5,139.75/x
3. Step 3: Cross multiply
   2,179.50x = 5,139.75 × 5,139.75
4. Step 4: Simplify right side
   2,179.50x = 26,417,030.06
5. Step 5: Solve for x
   x = 26,417,030.06/2,179.50
6. Step 6: Final answer
   x = 12,120.68