Finding the Fourth Proportional to 128,909.76, 177,894.72 and 72,321

Step by Step Solution

1. Step 1: Write the proportion equation
   128,909.76 : 177,894.72 = 72,321 : x
2. Step 2: Convert to fraction form
   128,909.76/177,894.72 = 72,321/x
3. Step 3: Cross multiply
   128,909.76x = 177,894.72 × 72,321
4. Step 4: Simplify right side
   128,909.76x = 12,865,524,045.12
5. Step 5: Solve for x
   x = 12,865,524,045.12/128,909.76
6. Step 6: Final answer
   x = 99,802.56