Finding the Third Proportional to 2,485.50 and 5,128.50

Step by Step Solution

1. Step 1: Write the proportion equation
   2,485.50 : 5,128.50 = 5,128.50 : x
2. Step 2: Convert to fraction form
   2,485.50/5,128.50 = 5,128.50/x
3. Step 3: Cross multiply
   2,485.50x = 5,128.50 × 5,128.50
4. Step 4: Simplify right side
   2,485.50x = 26,301,512.25
5. Step 5: Solve for x
   x = 26,301,512.25/2,485.50
6. Step 6: Final answer
   x = 10,581.98