Finding the Third Proportional to 12,840 and 18,028.50

Step by Step Solution

1. Step 1: Write the proportion equation
   12,840 : 18,028.50 = 18,028.50 : x
2. Step 2: Convert to fraction form
   12,840/18,028.50 = 18,028.50/x
3. Step 3: Cross multiply
   12,840x = 18,028.50 × 18,028.50
4. Step 4: Simplify right side
   12,840x = 325,026,812.25
5. Step 5: Solve for x
   x = 325,026,812.25/12,840
6. Step 6: Final answer
   x = 25,313.61