Finding the Third Proportional to 663.75 and 1,290.38

Step by Step Solution

1. Step 1: Write the proportion equation
   663.75 : 1,290.38 = 1,290.38 : x
2. Step 2: Convert to fraction form
   663.75/1,290.38 = 1,290.38/x
3. Step 3: Cross multiply
   663.75x = 1,290.38 × 1,290.38
4. Step 4: Simplify right side
   663.75x = 1,665,067.64
5. Step 5: Solve for x
   x = 1,665,067.64/663.75
6. Step 6: Final answer
   x = 2,508.58