Finding the Fourth Proportional to 1,387.88, 1,915.27 and 766.88

Step by Step Solution

1. Step 1: Write the proportion equation
   1,387.88 : 1,915.27 = 766.88 : x
2. Step 2: Convert to fraction form
   1,387.88/1,915.27 = 766.88/x
3. Step 3: Cross multiply
   1,387.88x = 1,915.27 × 766.88
4. Step 4: Simplify right side
   1,387.88x = 1,468,770.76
5. Step 5: Solve for x
   x = 1,468,770.76/1,387.88
6. Step 6: Final answer
   x = 1,058.29