Finding the Fourth Proportional to 9,401.72, 12,972.40 and 5,421.80

Step by Step Solution

1. Step 1: Write the proportion equation
   9,401.72 : 12,972.40 = 5,421.80 : x
2. Step 2: Convert to fraction form
   9,401.72/12,972.40 = 5,421.80/x
3. Step 3: Cross multiply
   9,401.72x = 12,972.40 × 5,421.80
4. Step 4: Simplify right side
   9,401.72x = 70,333,758.32
5. Step 5: Solve for x
   x = 70,333,758.32/9,401.72
6. Step 6: Final answer
   x = 7,480.95