Finding the Fourth Proportional to 2,085.90, 3,129.71 and 915.29

Step by Step Solution

1. Step 1: Write the proportion equation
   2,085.90 : 3,129.71 = 915.29 : x
2. Step 2: Convert to fraction form
   2,085.90/3,129.71 = 915.29/x
3. Step 3: Cross multiply
   2,085.90x = 3,129.71 × 915.29
4. Step 4: Simplify right side
   2,085.90x = 2,864,592.27
5. Step 5: Solve for x
   x = 2,864,592.27/2,085.90
6. Step 6: Final answer
   x = 1,373.31