Finding the Fourth Proportional to 5,173.31, 7,139.15 and 2,815.45

Step by Step Solution

1. Step 1: Write the proportion equation
   5,173.31 : 7,139.15 = 2,815.45 : x
2. Step 2: Convert to fraction form
   5,173.31/7,139.15 = 2,815.45/x
3. Step 3: Cross multiply
   5,173.31x = 7,139.15 × 2,815.45
4. Step 4: Simplify right side
   5,173.31x = 20,099,919.87
5. Step 5: Solve for x
   x = 20,099,919.87/5,173.31
6. Step 6: Final answer
   x = 3,885.31