Finding the Fourth Proportional to 12,478.86, 17,221.14 and 7,172.64

Step by Step Solution

1. Step 1: Write the proportion equation
   12,478.86 : 17,221.14 = 7,172.64 : x
2. Step 2: Convert to fraction form
   12,478.86/17,221.14 = 7,172.64/x
3. Step 3: Cross multiply
   12,478.86x = 17,221.14 × 7,172.64
4. Step 4: Simplify right side
   12,478.86x = 123,521,037.61
5. Step 5: Solve for x
   x = 123,521,037.61/12,478.86
6. Step 6: Final answer
   x = 9,898.42