Finding the Fourth Proportional to 9,131.10, 13,688.55 and 5,429.40

Step by Step Solution

1. Step 1: Write the proportion equation
   9,131.10 : 13,688.55 = 5,429.40 : x
2. Step 2: Convert to fraction form
   9,131.10/13,688.55 = 5,429.40/x
3. Step 3: Cross multiply
   9,131.10x = 13,688.55 × 5,429.40
4. Step 4: Simplify right side
   9,131.10x = 74,320,613.37
5. Step 5: Solve for x
   x = 74,320,613.37/9,131.10
6. Step 6: Final answer
   x = 8,139.28