Finding the Fourth Proportional to 9,415.31, 12,991.16 and 5,436.23

Step by Step Solution

1. Step 1: Write the proportion equation
   9,415.31 : 12,991.16 = 5,436.23 : x
2. Step 2: Convert to fraction form
   9,415.31/12,991.16 = 5,436.23/x
3. Step 3: Cross multiply
   9,415.31x = 12,991.16 × 5,436.23
4. Step 4: Simplify right side
   9,415.31x = 70,622,882.36
5. Step 5: Solve for x
   x = 70,622,882.36/9,415.31
6. Step 6: Final answer
   x = 7,500.86