Finding the Fourth Proportional to 9,991.35, 13,787.98 and 5,515.10

Step by Step Solution

1. Step 1: Write the proportion equation
   9,991.35 : 13,787.98 = 5,515.10 : x
2. Step 2: Convert to fraction form
   9,991.35/13,787.98 = 5,515.10/x
3. Step 3: Cross multiply
   9,991.35x = 13,787.98 × 5,515.10
4. Step 4: Simplify right side
   9,991.35x = 76,042,036.79
5. Step 5: Solve for x
   x = 76,042,036.79/9,991.35
6. Step 6: Final answer
   x = 7,610.79