Finding the Fourth Proportional to 9,315.56, 12,855.36 and 5,123.72

Step by Step Solution

1. Step 1: Write the proportion equation
   9,315.56 : 12,855.36 = 5,123.72 : x
2. Step 2: Convert to fraction form
   9,315.56/12,855.36 = 5,123.72/x
3. Step 3: Cross multiply
   9,315.56x = 12,855.36 × 5,123.72
4. Step 4: Simplify right side
   9,315.56x = 65,867,265.14
5. Step 5: Solve for x
   x = 65,867,265.14/9,315.56
6. Step 6: Final answer
   x = 7,070.67