Finding the Fourth Proportional to 28,245.57, 38,979.61 and 15,499.30

Step by Step Solution

1. Step 1: Write the proportion equation
   28,245.57 : 38,979.61 = 15,499.30 : x
2. Step 2: Convert to fraction form
   28,245.57/38,979.61 = 15,499.30/x
3. Step 3: Cross multiply
   28,245.57x = 38,979.61 × 15,499.30
4. Step 4: Simplify right side
   28,245.57x = 604,156,669.27
5. Step 5: Solve for x
   x = 604,156,669.27/28,245.57
6. Step 6: Final answer
   x = 21,389.43