Finding the Fourth Proportional to 12,820.70, 17,689.56 and 7,784.78

Step by Step Solution

1. Step 1: Write the proportion equation
   12,820.70 : 17,689.56 = 7,784.78 : x
2. Step 2: Convert to fraction form
   12,820.70/17,689.56 = 7,784.78/x
3. Step 3: Cross multiply
   12,820.70x = 17,689.56 × 7,784.78
4. Step 4: Simplify right side
   12,820.70x = 137,709,332.90
5. Step 5: Solve for x
   x = 137,709,332.90/12,820.70
6. Step 6: Final answer
   x = 10,741.17