Finding the Fourth Proportional to 3,990.88, 5,507.42 and 2,312.61

Step by Step Solution

1. Step 1: Write the proportion equation
   3,990.88 : 5,507.42 = 2,312.61 : x
2. Step 2: Convert to fraction form
   3,990.88/5,507.42 = 2,312.61/x
3. Step 3: Cross multiply
   3,990.88x = 5,507.42 × 2,312.61
4. Step 4: Simplify right side
   3,990.88x = 12,736,495.02
5. Step 5: Solve for x
   x = 12,736,495.02/3,990.88
6. Step 6: Final answer
   x = 3,191.40