Finding the Fourth Proportional to 28,308.72, 42,510.60 and 21,288.72

Step by Step Solution

1. Step 1: Write the proportion equation
   28,308.72 : 42,510.60 = 21,288.72 : x
2. Step 2: Convert to fraction form
   28,308.72/42,510.60 = 21,288.72/x
3. Step 3: Cross multiply
   28,308.72x = 42,510.60 × 21,288.72
4. Step 4: Simplify right side
   28,308.72x = 904,996,260.43
5. Step 5: Solve for x
   x = 904,996,260.43/28,308.72
6. Step 6: Final answer
   x = 31,968.82