Finding the Fourth Proportional to 9,315.81, 12,858.35 and 5,490.79

Step by Step Solution

1. Step 1: Write the proportion equation
   9,315.81 : 12,858.35 = 5,490.79 : x
2. Step 2: Convert to fraction form
   9,315.81/12,858.35 = 5,490.79/x
3. Step 3: Cross multiply
   9,315.81x = 12,858.35 × 5,490.79
4. Step 4: Simplify right side
   9,315.81x = 70,602,440.00
5. Step 5: Solve for x
   x = 70,602,440.00/9,315.81
6. Step 6: Final answer
   x = 7,578.78