Finding the Third Proportional to 820.13 and 1,321.31

Step by Step Solution

1. Step 1: Write the proportion equation
   820.13 : 1,321.31 = 1,321.31 : x
2. Step 2: Convert to fraction form
   820.13/1,321.31 = 1,321.31/x
3. Step 3: Cross multiply
   820.13x = 1,321.31 × 1,321.31
4. Step 4: Simplify right side
   820.13x = 1,745,866.72
5. Step 5: Solve for x
   x = 1,745,866.72/820.13
6. Step 6: Final answer
   x = 2,128.78