Finding the Fourth Proportional to 8,990.90, 13,485.89 and 3,147.05

Step by Step Solution

1. Step 1: Write the proportion equation
   8,990.90 : 13,485.89 = 3,147.05 : x
2. Step 2: Convert to fraction form
   8,990.90/13,485.89 = 3,147.05/x
3. Step 3: Cross multiply
   8,990.90x = 13,485.89 × 3,147.05
4. Step 4: Simplify right side
   8,990.90x = 42,440,811.71
5. Step 5: Solve for x
   x = 42,440,811.71/8,990.90
6. Step 6: Final answer
   x = 4,720.42