Finding the Fourth Proportional to 9,415.18, 12,990.85 and 5,435.43

Step by Step Solution

1. Step 1: Write the proportion equation
   9,415.18 : 12,990.85 = 5,435.43 : x
2. Step 2: Convert to fraction form
   9,415.18/12,990.85 = 5,435.43/x
3. Step 3: Cross multiply
   9,415.18x = 12,990.85 × 5,435.43
4. Step 4: Simplify right side
   9,415.18x = 70,610,855.82
5. Step 5: Solve for x
   x = 70,610,855.82/9,415.18
6. Step 6: Final answer
   x = 7,499.68