Finding the Fourth Proportional to 12,388.78, 18,578.31 and 4,991.86

Step by Step Solution

1. Step 1: Write the proportion equation
   12,388.78 : 18,578.31 = 4,991.86 : x
2. Step 2: Convert to fraction form
   12,388.78/18,578.31 = 4,991.86/x
3. Step 3: Cross multiply
   12,388.78x = 18,578.31 × 4,991.86
4. Step 4: Simplify right side
   12,388.78x = 92,740,322.56
5. Step 5: Solve for x
   x = 92,740,322.56/12,388.78
6. Step 6: Final answer
   x = 7,485.83