Finding the Third Proportional to 661.78 and 1,018.55

Step by Step Solution

1. Step 1: Write the proportion equation
   661.78 : 1,018.55 = 1,018.55 : x
2. Step 2: Convert to fraction form
   661.78/1,018.55 = 1,018.55/x
3. Step 3: Cross multiply
   661.78x = 1,018.55 × 1,018.55
4. Step 4: Simplify right side
   661.78x = 1,037,437.74
5. Step 5: Solve for x
   x = 1,037,437.74/661.78
6. Step 6: Final answer
   x = 1,567.64