Finding the Fourth Proportional to 9,991.77, 13,788.71 and 5,515.55

Step by Step Solution

1. Step 1: Write the proportion equation
   9,991.77 : 13,788.71 = 5,515.55 : x
2. Step 2: Convert to fraction form
   9,991.77/13,788.71 = 5,515.55/x
3. Step 3: Cross multiply
   9,991.77x = 13,788.71 × 5,515.55
4. Step 4: Simplify right side
   9,991.77x = 76,052,222.92
5. Step 5: Solve for x
   x = 76,052,222.92/9,991.77
6. Step 6: Final answer
   x = 7,611.49