Finding the Third Proportional to 678.80 and 1,097.72

Step by Step Solution

1. Step 1: Write the proportion equation
   678.80 : 1,097.72 = 1,097.72 : x
2. Step 2: Convert to fraction form
   678.80/1,097.72 = 1,097.72/x
3. Step 3: Cross multiply
   678.80x = 1,097.72 × 1,097.72
4. Step 4: Simplify right side
   678.80x = 1,204,986.45
5. Step 5: Solve for x
   x = 1,204,986.45/678.80
6. Step 6: Final answer
   x = 1,775.18