Finding the Fourth Proportional to 1,435.31, 2,156.57 and 915.55

Step by Step Solution

1. Step 1: Write the proportion equation
   1,435.31 : 2,156.57 = 915.55 : x
2. Step 2: Convert to fraction form
   1,435.31/2,156.57 = 915.55/x
3. Step 3: Cross multiply
   1,435.31x = 2,156.57 × 915.55
4. Step 4: Simplify right side
   1,435.31x = 1,974,447.66
5. Step 5: Solve for x
   x = 1,974,447.66/1,435.31
6. Step 6: Final answer
   x = 1,375.62