Finding the Fourth Proportional to 1,387.88, 1,915.62 and 864.52

Step by Step Solution

1. Step 1: Write the proportion equation
   1,387.88 : 1,915.62 = 864.52 : x
2. Step 2: Convert to fraction form
   1,387.88/1,915.62 = 864.52/x
3. Step 3: Cross multiply
   1,387.88x = 1,915.62 × 864.52
4. Step 4: Simplify right side
   1,387.88x = 1,656,091.80
5. Step 5: Solve for x
   x = 1,656,091.80/1,387.88
6. Step 6: Final answer
   x = 1,193.25