Finding the Third Proportional to 640.88 and 1,069.50

Step by Step Solution

1. Step 1: Write the proportion equation
   640.88 : 1,069.50 = 1,069.50 : x
2. Step 2: Convert to fraction form
   640.88/1,069.50 = 1,069.50/x
3. Step 3: Cross multiply
   640.88x = 1,069.50 × 1,069.50
4. Step 4: Simplify right side
   640.88x = 1,143,830.25
5. Step 5: Solve for x
   x = 1,143,830.25/640.88
6. Step 6: Final answer
   x = 1,784.79