Finding the Fourth Proportional to 9,439.80, 14,215.89 and 8,221.91

Step by Step Solution

1. Step 1: Write the proportion equation
   9,439.80 : 14,215.89 = 8,221.91 : x
2. Step 2: Convert to fraction form
   9,439.80/14,215.89 = 8,221.91/x
3. Step 3: Cross multiply
   9,439.80x = 14,215.89 × 8,221.91
4. Step 4: Simplify right side
   9,439.80x = 116,881,772.86
5. Step 5: Solve for x
   x = 116,881,772.86/9,439.80
6. Step 6: Final answer
   x = 12,381.81