Finding the Fourth Proportional to 19,978.40, 27,580.17 and 12,427.16

Step by Step Solution

1. Step 1: Write the proportion equation
   19,978.40 : 27,580.17 = 12,427.16 : x
2. Step 2: Convert to fraction form
   19,978.40/27,580.17 = 12,427.16/x
3. Step 3: Cross multiply
   19,978.40x = 27,580.17 × 12,427.16
4. Step 4: Simplify right side
   19,978.40x = 342,743,185.42
5. Step 5: Solve for x
   x = 342,743,185.42/19,978.40
6. Step 6: Final answer
   x = 17,155.69