Finding the Fourth Proportional to 9,415.49, 12,991.86 and 5,435.87

Step by Step Solution

1. Step 1: Write the proportion equation
   9,415.49 : 12,991.86 = 5,435.87 : x
2. Step 2: Convert to fraction form
   9,415.49/12,991.86 = 5,435.87/x
3. Step 3: Cross multiply
   9,415.49x = 12,991.86 × 5,435.87
4. Step 4: Simplify right side
   9,415.49x = 70,621,997.06
5. Step 5: Solve for x
   x = 70,621,997.06/9,415.49
6. Step 6: Final answer
   x = 7,500.62