Finding the Fourth Proportional to 6,780.72, 9,357.72 and 3,985.20

Step by Step Solution

1. Step 1: Write the proportion equation
   6,780.72 : 9,357.72 = 3,985.20 : x
2. Step 2: Convert to fraction form
   6,780.72/9,357.72 = 3,985.20/x
3. Step 3: Cross multiply
   6,780.72x = 9,357.72 × 3,985.20
4. Step 4: Simplify right side
   6,780.72x = 37,292,385.74
5. Step 5: Solve for x
   x = 37,292,385.74/6,780.72
6. Step 6: Final answer
   x = 5,499.77