Finding the Fourth Proportional to 13,521.86, 18,658.89 and 7,931.78

Step by Step Solution

1. Step 1: Write the proportion equation
   13,521.86 : 18,658.89 = 7,931.78 : x
2. Step 2: Convert to fraction form
   13,521.86/18,658.89 = 7,931.78/x
3. Step 3: Cross multiply
   13,521.86x = 18,658.89 × 7,931.78
4. Step 4: Simplify right side
   13,521.86x = 147,998,210.52
5. Step 5: Solve for x
   x = 147,998,210.52/13,521.86
6. Step 6: Final answer
   x = 10,945.11