Finding the Fourth Proportional to 1,387.80, 1,915.16 and 758.31

Step by Step Solution

1. Step 1: Write the proportion equation
   1,387.80 : 1,915.16 = 758.31 : x
2. Step 2: Convert to fraction form
   1,387.80/1,915.16 = 758.31/x
3. Step 3: Cross multiply
   1,387.80x = 1,915.16 × 758.31
4. Step 4: Simplify right side
   1,387.80x = 1,452,281.19
5. Step 5: Solve for x
   x = 1,452,281.19/1,387.80
6. Step 6: Final answer
   x = 1,046.46