Finding the Fourth Proportional to 9,997.80, 14,978.70 and 7,931.40

Step by Step Solution

1. Step 1: Write the proportion equation
   9,997.80 : 14,978.70 = 7,931.40 : x
2. Step 2: Convert to fraction form
   9,997.80/14,978.70 = 7,931.40/x
3. Step 3: Cross multiply
   9,997.80x = 14,978.70 × 7,931.40
4. Step 4: Simplify right side
   9,997.80x = 118,802,061.18
5. Step 5: Solve for x
   x = 118,802,061.18/9,997.80
6. Step 6: Final answer
   x = 11,882.82