Finding the Fourth Proportional to 21,838.76, 30,138.72 and 12,409.28

Step by Step Solution

1. Step 1: Write the proportion equation
   21,838.76 : 30,138.72 = 12,409.28 : x
2. Step 2: Convert to fraction form
   21,838.76/30,138.72 = 12,409.28/x
3. Step 3: Cross multiply
   21,838.76x = 30,138.72 × 12,409.28
4. Step 4: Simplify right side
   21,838.76x = 373,999,815.32
5. Step 5: Solve for x
   x = 373,999,815.32/21,838.76
6. Step 6: Final answer
   x = 17,125.51