Finding the Fourth Proportional to 21,878.31, 30,191.36 and 12,318.69

Step by Step Solution

1. Step 1: Write the proportion equation
   21,878.31 : 30,191.36 = 12,318.69 : x
2. Step 2: Convert to fraction form
   21,878.31/30,191.36 = 12,318.69/x
3. Step 3: Cross multiply
   21,878.31x = 30,191.36 × 12,318.69
4. Step 4: Simplify right side
   21,878.31x = 371,918,004.52
5. Step 5: Solve for x
   x = 371,918,004.52/21,878.31
6. Step 6: Final answer
   x = 16,999.39