Finding the Fourth Proportional to 31,078.35, 42,874.45 and 21,003.12

Step by Step Solution

1. Step 1: Write the proportion equation
   31,078.35 : 42,874.45 = 21,003.12 : x
2. Step 2: Convert to fraction form
   31,078.35/42,874.45 = 21,003.12/x
3. Step 3: Cross multiply
   31,078.35x = 42,874.45 × 21,003.12
4. Step 4: Simplify right side
   31,078.35x = 900,497,218.28
5. Step 5: Solve for x
   x = 900,497,218.28/31,078.35
6. Step 6: Final answer
   x = 28,975.07