Finding the Fourth Proportional to 12,128, 18,194.88 and 3,920

Step by Step Solution

1. Step 1: Write the proportion equation
   12,128 : 18,194.88 = 3,920 : x
2. Step 2: Convert to fraction form
   12,128/18,194.88 = 3,920/x
3. Step 3: Cross multiply
   12,128x = 18,194.88 × 3,920
4. Step 4: Simplify right side
   12,128x = 71,323,929.60
5. Step 5: Solve for x
   x = 71,323,929.60/12,128
6. Step 6: Final answer
   x = 5,880.93