Finding the Fourth Proportional to 13,439.78, 18,547.55 and 7,471.31

Step by Step Solution

1. Step 1: Write the proportion equation
   13,439.78 : 18,547.55 = 7,471.31 : x
2. Step 2: Convert to fraction form
   13,439.78/18,547.55 = 7,471.31/x
3. Step 3: Cross multiply
   13,439.78x = 18,547.55 × 7,471.31
4. Step 4: Simplify right side
   13,439.78x = 138,574,504.80
5. Step 5: Solve for x
   x = 138,574,504.80/13,439.78
6. Step 6: Final answer
   x = 10,310.78