Finding the Fourth Proportional to 5,638.72, 7,781.32 and 3,120.69

Step by Step Solution

1. Step 1: Write the proportion equation
   5,638.72 : 7,781.32 = 3,120.69 : x
2. Step 2: Convert to fraction form
   5,638.72/7,781.32 = 3,120.69/x
3. Step 3: Cross multiply
   5,638.72x = 7,781.32 × 3,120.69
4. Step 4: Simplify right side
   5,638.72x = 24,283,048.60
5. Step 5: Solve for x
   x = 24,283,048.60/5,638.72
6. Step 6: Final answer
   x = 4,306.48