Finding the Fourth Proportional to 31,017.40, 42,810.20 and 18,439.72

Step by Step Solution

1. Step 1: Write the proportion equation
   31,017.40 : 42,810.20 = 18,439.72 : x
2. Step 2: Convert to fraction form
   31,017.40/42,810.20 = 18,439.72/x
3. Step 3: Cross multiply
   31,017.40x = 42,810.20 × 18,439.72
4. Step 4: Simplify right side
   31,017.40x = 789,408,101.14
5. Step 5: Solve for x
   x = 789,408,101.14/31,017.40
6. Step 6: Final answer
   x = 25,450.49