Finding the Fourth Proportional to 9,978.36, 13,758.90 and 6,388.62

Step by Step Solution

1. Step 1: Write the proportion equation
   9,978.36 : 13,758.90 = 6,388.62 : x
2. Step 2: Convert to fraction form
   9,978.36/13,758.90 = 6,388.62/x
3. Step 3: Cross multiply
   9,978.36x = 13,758.90 × 6,388.62
4. Step 4: Simplify right side
   9,978.36x = 87,900,383.72
5. Step 5: Solve for x
   x = 87,900,383.72/9,978.36
6. Step 6: Final answer
   x = 8,809.10