Finding the Fourth Proportional to 9,401.70, 12,972.42 and 5,421.78

Step by Step Solution

1. Step 1: Write the proportion equation
   9,401.70 : 12,972.42 = 5,421.78 : x
2. Step 2: Convert to fraction form
   9,401.70/12,972.42 = 5,421.78/x
3. Step 3: Cross multiply
   9,401.70x = 12,972.42 × 5,421.78
4. Step 4: Simplify right side
   9,401.70x = 70,333,607.31
5. Step 5: Solve for x
   x = 70,333,607.31/9,401.70
6. Step 6: Final answer
   x = 7,480.95