Finding the Fourth Proportional to 10,147.50, 15,221.34 and 3,991.50

Step by Step Solution

1. Step 1: Write the proportion equation
   10,147.50 : 15,221.34 = 3,991.50 : x
2. Step 2: Convert to fraction form
   10,147.50/15,221.34 = 3,991.50/x
3. Step 3: Cross multiply
   10,147.50x = 15,221.34 × 3,991.50
4. Step 4: Simplify right side
   10,147.50x = 60,755,978.61
5. Step 5: Solve for x
   x = 60,755,978.61/10,147.50
6. Step 6: Final answer
   x = 5,987.29