Finding the Fourth Proportional to 20,296.69, 28,007.46 and 12,740.60

Step by Step Solution

1. Step 1: Write the proportion equation
   20,296.69 : 28,007.46 = 12,740.60 : x
2. Step 2: Convert to fraction form
   20,296.69/28,007.46 = 12,740.60/x
3. Step 3: Cross multiply
   20,296.69x = 28,007.46 × 12,740.60
4. Step 4: Simplify right side
   20,296.69x = 356,831,914.89
5. Step 5: Solve for x
   x = 356,831,914.89/20,296.69
6. Step 6: Final answer
   x = 17,580.80