Finding the Fourth Proportional to 13,131.72, 19,701.57 and 7,872.57

Step by Step Solution

1. Step 1: Write the proportion equation
   13,131.72 : 19,701.57 = 7,872.57 : x
2. Step 2: Convert to fraction form
   13,131.72/19,701.57 = 7,872.57/x
3. Step 3: Cross multiply
   13,131.72x = 19,701.57 × 7,872.57
4. Step 4: Simplify right side
   13,131.72x = 155,101,988.93
5. Step 5: Solve for x
   x = 155,101,988.93/13,131.72
6. Step 6: Final answer
   x = 11,811.25