Finding the Fourth Proportional to 1,405.76, 1,938.88 and 939.20

Step by Step Solution

1. Step 1: Write the proportion equation
   1,405.76 : 1,938.88 = 939.20 : x
2. Step 2: Convert to fraction form
   1,405.76/1,938.88 = 939.20/x
3. Step 3: Cross multiply
   1,405.76x = 1,938.88 × 939.20
4. Step 4: Simplify right side
   1,405.76x = 1,820,996.10
5. Step 5: Solve for x
   x = 1,820,996.10/1,405.76
6. Step 6: Final answer
   x = 1,295.38