Finding the Fourth Proportional to 13,581.69, 20,369.76 and 3,720.21

Step by Step Solution

1. Step 1: Write the proportion equation
   13,581.69 : 20,369.76 = 3,720.21 : x
2. Step 2: Convert to fraction form
   13,581.69/20,369.76 = 3,720.21/x
3. Step 3: Cross multiply
   13,581.69x = 20,369.76 × 3,720.21
4. Step 4: Simplify right side
   13,581.69x = 75,779,784.85
5. Step 5: Solve for x
   x = 75,779,784.85/13,581.69
6. Step 6: Final answer
   x = 5,579.55