Finding the Fourth Proportional to 1,388.31, 1,915.76 and 767.31

Step by Step Solution

1. Step 1: Write the proportion equation
   1,388.31 : 1,915.76 = 767.31 : x
2. Step 2: Convert to fraction form
   1,388.31/1,915.76 = 767.31/x
3. Step 3: Cross multiply
   1,388.31x = 1,915.76 × 767.31
4. Step 4: Simplify right side
   1,388.31x = 1,469,977.97
5. Step 5: Solve for x
   x = 1,469,977.97/1,388.31
6. Step 6: Final answer
   x = 1,058.83