Finding the Fourth Proportional to 12,931.25, 19,400.45 and 5,145.53

Step by Step Solution

1. Step 1: Write the proportion equation
   12,931.25 : 19,400.45 = 5,145.53 : x
2. Step 2: Convert to fraction form
   12,931.25/19,400.45 = 5,145.53/x
3. Step 3: Cross multiply
   12,931.25x = 19,400.45 × 5,145.53
4. Step 4: Simplify right side
   12,931.25x = 99,825,474.76
5. Step 5: Solve for x
   x = 99,825,474.76/12,931.25
6. Step 6: Final answer
   x = 7,719.71