Finding the Fourth Proportional to 21,007.80, 28,989.54 and 13,050.72

Step by Step Solution

1. Step 1: Write the proportion equation
   21,007.80 : 28,989.54 = 13,050.72 : x
2. Step 2: Convert to fraction form
   21,007.80/28,989.54 = 13,050.72/x
3. Step 3: Cross multiply
   21,007.80x = 28,989.54 × 13,050.72
4. Step 4: Simplify right side
   21,007.80x = 378,334,369.47
5. Step 5: Solve for x
   x = 378,334,369.47/21,007.80
6. Step 6: Final answer
   x = 18,009.23