Finding the Fourth Proportional to 31,153.89, 42,987.30 and 18,405.30

Step by Step Solution

1. Step 1: Write the proportion equation
   31,153.89 : 42,987.30 = 18,405.30 : x
2. Step 2: Convert to fraction form
   31,153.89/42,987.30 = 18,405.30/x
3. Step 3: Cross multiply
   31,153.89x = 42,987.30 × 18,405.30
4. Step 4: Simplify right side
   31,153.89x = 791,194,152.69
5. Step 5: Solve for x
   x = 791,194,152.69/31,153.89
6. Step 6: Final answer
   x = 25,396.32