Finding the Fourth Proportional to 30,618.78, 42,258.54 and 18,689.05

Step by Step Solution

1. Step 1: Write the proportion equation
   30,618.78 : 42,258.54 = 18,689.05 : x
2. Step 2: Convert to fraction form
   30,618.78/42,258.54 = 18,689.05/x
3. Step 3: Cross multiply
   30,618.78x = 42,258.54 × 18,689.05
4. Step 4: Simplify right side
   30,618.78x = 789,772,051.06
5. Step 5: Solve for x
   x = 789,772,051.06/30,618.78
6. Step 6: Final answer
   x = 25,793.71