Finding the Fourth Proportional to 21,005.50, 28,987.71 and 11,445.50

Step by Step Solution

1. Step 1: Write the proportion equation
   21,005.50 : 28,987.71 = 11,445.50 : x
2. Step 2: Convert to fraction form
   21,005.50/28,987.71 = 11,445.50/x
3. Step 3: Cross multiply
   21,005.50x = 28,987.71 × 11,445.50
4. Step 4: Simplify right side
   21,005.50x = 331,778,632.64
5. Step 5: Solve for x
   x = 331,778,632.64/21,005.50
6. Step 6: Final answer
   x = 15,794.85