Finding the Third Proportional to 559.78 and 661.03

Step by Step Solution

1. Step 1: Write the proportion equation
   559.78 : 661.03 = 661.03 : x
2. Step 2: Convert to fraction form
   559.78/661.03 = 661.03/x
3. Step 3: Cross multiply
   559.78x = 661.03 × 661.03
4. Step 4: Simplify right side
   559.78x = 436,962.31
5. Step 5: Solve for x
   x = 436,962.31/559.78
6. Step 6: Final answer
   x = 780.59