Finding the Fourth Proportional to 1,387.78, 1,915.14 and 758.31

Step by Step Solution

1. Step 1: Write the proportion equation
   1,387.78 : 1,915.14 = 758.31 : x
2. Step 2: Convert to fraction form
   1,387.78/1,915.14 = 758.31/x
3. Step 3: Cross multiply
   1,387.78x = 1,915.14 × 758.31
4. Step 4: Simplify right side
   1,387.78x = 1,452,266.02
5. Step 5: Solve for x
   x = 1,452,266.02/1,387.78
6. Step 6: Final answer
   x = 1,046.47