Finding the Fourth Proportional to 1,380.61, 1,904.52 and 938.80

Step by Step Solution

1. Step 1: Write the proportion equation
   1,380.61 : 1,904.52 = 938.80 : x
2. Step 2: Convert to fraction form
   1,380.61/1,904.52 = 938.80/x
3. Step 3: Cross multiply
   1,380.61x = 1,904.52 × 938.80
4. Step 4: Simplify right side
   1,380.61x = 1,787,963.38
5. Step 5: Solve for x
   x = 1,787,963.38/1,380.61
6. Step 6: Final answer
   x = 1,295.05