Finding the Fourth Proportional to 31,080.40, 42,791.88 and 28,960.72

Step by Step Solution

1. Step 1: Write the proportion equation
   31,080.40 : 42,791.88 = 28,960.72 : x
2. Step 2: Convert to fraction form
   31,080.40/42,791.88 = 28,960.72/x
3. Step 3: Cross multiply
   31,080.40x = 42,791.88 × 28,960.72
4. Step 4: Simplify right side
   31,080.40x = 1,239,283,654.95
5. Step 5: Solve for x
   x = 1,239,283,654.95/31,080.40
6. Step 6: Final answer
   x = 39,873.48