Finding the Fourth Proportional to 28,555.48, 42,828.54 and 7,780.60

Step by Step Solution

1. Step 1: Write the proportion equation
   28,555.48 : 42,828.54 = 7,780.60 : x
2. Step 2: Convert to fraction form
   28,555.48/42,828.54 = 7,780.60/x
3. Step 3: Cross multiply
   28,555.48x = 42,828.54 × 7,780.60
4. Step 4: Simplify right side
   28,555.48x = 333,231,738.32
5. Step 5: Solve for x
   x = 333,231,738.32/28,555.48
6. Step 6: Final answer
   x = 11,669.62