Finding the Fourth Proportional to 209,188.72, 288,684.84 and 128,661.76

Step by Step Solution

1. Step 1: Write the proportion equation
   209,188.72 : 288,684.84 = 128,661.76 : x
2. Step 2: Convert to fraction form
   209,188.72/288,684.84 = 128,661.76/x
3. Step 3: Cross multiply
   209,188.72x = 288,684.84 × 128,661.76
4. Step 4: Simplify right side
   209,188.72x = 37,142,699,599.72
5. Step 5: Solve for x
   x = 37,142,699,599.72/209,188.72
6. Step 6: Final answer
   x = 177,555.94