Finding the Fourth Proportional to 31,078.80, 42,874.05 and 21,010.77

Step by Step Solution

1. Step 1: Write the proportion equation
   31,078.80 : 42,874.05 = 21,010.77 : x
2. Step 2: Convert to fraction form
   31,078.80/42,874.05 = 21,010.77/x
3. Step 3: Cross multiply
   31,078.80x = 42,874.05 × 21,010.77
4. Step 4: Simplify right side
   31,078.80x = 900,816,803.52
5. Step 5: Solve for x
   x = 900,816,803.52/31,078.80
6. Step 6: Final answer
   x = 28,984.93