Finding the Fourth Proportional to 12,911.50, 17,820.91 and 7,879.88

Step by Step Solution

1. Step 1: Write the proportion equation
   12,911.50 : 17,820.91 = 7,879.88 : x
2. Step 2: Convert to fraction form
   12,911.50/17,820.91 = 7,879.88/x
3. Step 3: Cross multiply
   12,911.50x = 17,820.91 × 7,879.88
4. Step 4: Simplify right side
   12,911.50x = 140,426,657.14
5. Step 5: Solve for x
   x = 140,426,657.14/12,911.50
6. Step 6: Final answer
   x = 10,876.09