Finding the Fourth Proportional to 21,131.52, 31,701.60 and 7,278.72

Step by Step Solution

1. Step 1: Write the proportion equation
   21,131.52 : 31,701.60 = 7,278.72 : x
2. Step 2: Convert to fraction form
   21,131.52/31,701.60 = 7,278.72/x
3. Step 3: Cross multiply
   21,131.52x = 31,701.60 × 7,278.72
4. Step 4: Simplify right side
   21,131.52x = 230,747,069.95
5. Step 5: Solve for x
   x = 230,747,069.95/21,131.52
6. Step 6: Final answer
   x = 10,919.57