Finding the Fourth Proportional to 9,899.85, 13,661.79 and 5,423.88

Step by Step Solution

1. Step 1: Write the proportion equation
   9,899.85 : 13,661.79 = 5,423.88 : x
2. Step 2: Convert to fraction form
   9,899.85/13,661.79 = 5,423.88/x
3. Step 3: Cross multiply
   9,899.85x = 13,661.79 × 5,423.88
4. Step 4: Simplify right side
   9,899.85x = 74,099,909.55
5. Step 5: Solve for x
   x = 74,099,909.55/9,899.85
6. Step 6: Final answer
   x = 7,484.95