Finding the Fourth Proportional to 1,387.18, 1,915.01 and 863.38

Step by Step Solution

1. Step 1: Write the proportion equation
   1,387.18 : 1,915.01 = 863.38 : x
2. Step 2: Convert to fraction form
   1,387.18/1,915.01 = 863.38/x
3. Step 3: Cross multiply
   1,387.18x = 1,915.01 × 863.38
4. Step 4: Simplify right side
   1,387.18x = 1,653,381.33
5. Step 5: Solve for x
   x = 1,653,381.33/1,387.18
6. Step 6: Final answer
   x = 1,191.90