Finding the Fourth Proportional to 12,987.10, 17,917.90 and 7,321.15

Step by Step Solution

1. Step 1: Write the proportion equation
   12,987.10 : 17,917.90 = 7,321.15 : x
2. Step 2: Convert to fraction form
   12,987.10/17,917.90 = 7,321.15/x
3. Step 3: Cross multiply
   12,987.10x = 17,917.90 × 7,321.15
4. Step 4: Simplify right side
   12,987.10x = 131,179,633.59
5. Step 5: Solve for x
   x = 131,179,633.59/12,987.10
6. Step 6: Final answer
   x = 10,100.76