Finding the Fourth Proportional to 9,315.64, 12,855.32 and 5,123.89

Step by Step Solution

1. Step 1: Write the proportion equation
   9,315.64 : 12,855.32 = 5,123.89 : x
2. Step 2: Convert to fraction form
   9,315.64/12,855.32 = 5,123.89/x
3. Step 3: Cross multiply
   9,315.64x = 12,855.32 × 5,123.89
4. Step 4: Simplify right side
   9,315.64x = 65,869,245.59
5. Step 5: Solve for x
   x = 65,869,245.59/9,315.64
6. Step 6: Final answer
   x = 7,070.82