Finding the Fourth Proportional to 39,883.61, 55,036.78 and 21,978.61

Step by Step Solution

1. Step 1: Write the proportion equation
   39,883.61 : 55,036.78 = 21,978.61 : x
2. Step 2: Convert to fraction form
   39,883.61/55,036.78 = 21,978.61/x
3. Step 3: Cross multiply
   39,883.61x = 55,036.78 × 21,978.61
4. Step 4: Simplify right side
   39,883.61x = 1,209,631,964.60
5. Step 5: Solve for x
   x = 1,209,631,964.60/39,883.61
6. Step 6: Final answer
   x = 30,329.05