Finding the Fourth Proportional to 2,590.50, 3,885.78 and 642.72

Step by Step Solution

1. Step 1: Write the proportion equation
   2,590.50 : 3,885.78 = 642.72 : x
2. Step 2: Convert to fraction form
   2,590.50/3,885.78 = 642.72/x
3. Step 3: Cross multiply
   2,590.50x = 3,885.78 × 642.72
4. Step 4: Simplify right side
   2,590.50x = 2,497,468.52
5. Step 5: Solve for x
   x = 2,497,468.52/2,590.50
6. Step 6: Final answer
   x = 964.09