Finding the Fourth Proportional to 2,588.50, 3,882.78 and 640.72

Step by Step Solution

1. Step 1: Write the proportion equation
   2,588.50 : 3,882.78 = 640.72 : x
2. Step 2: Convert to fraction form
   2,588.50/3,882.78 = 640.72/x
3. Step 3: Cross multiply
   2,588.50x = 3,882.78 × 640.72
4. Step 4: Simplify right side
   2,588.50x = 2,487,774.80
5. Step 5: Solve for x
   x = 2,487,774.80/2,588.50
6. Step 6: Final answer
   x = 961.09