Finding the Fourth Proportional to 1,387.52, 1,915.30 and 863.45

Step by Step Solution

1. Step 1: Write the proportion equation
   1,387.52 : 1,915.30 = 863.45 : x
2. Step 2: Convert to fraction form
   1,387.52/1,915.30 = 863.45/x
3. Step 3: Cross multiply
   1,387.52x = 1,915.30 × 863.45
4. Step 4: Simplify right side
   1,387.52x = 1,653,765.79
5. Step 5: Solve for x
   x = 1,653,765.79/1,387.52
6. Step 6: Final answer
   x = 1,191.89