Finding the Fourth Proportional to 9,991.85, 13,787.77 and 5,515.31

Step by Step Solution

1. Step 1: Write the proportion equation
   9,991.85 : 13,787.77 = 5,515.31 : x
2. Step 2: Convert to fraction form
   9,991.85/13,787.77 = 5,515.31/x
3. Step 3: Cross multiply
   9,991.85x = 13,787.77 × 5,515.31
4. Step 4: Simplify right side
   9,991.85x = 76,043,825.76
5. Step 5: Solve for x
   x = 76,043,825.76/9,991.85
6. Step 6: Final answer
   x = 7,610.59