Finding the Fourth Proportional to 28,420.82, 42,612.18 and 13,621.67

Step by Step Solution

1. Step 1: Write the proportion equation
   28,420.82 : 42,612.18 = 13,621.67 : x
2. Step 2: Convert to fraction form
   28,420.82/42,612.18 = 13,621.67/x
3. Step 3: Cross multiply
   28,420.82x = 42,612.18 × 13,621.67
4. Step 4: Simplify right side
   28,420.82x = 580,448,949.59
5. Step 5: Solve for x
   x = 580,448,949.59/28,420.82
6. Step 6: Final answer
   x = 20,423.37