Finding the Fourth Proportional to 1,387.10, 1,914.60 and 915.34

Step by Step Solution

1. Step 1: Write the proportion equation
   1,387.10 : 1,914.60 = 915.34 : x
2. Step 2: Convert to fraction form
   1,387.10/1,914.60 = 915.34/x
3. Step 3: Cross multiply
   1,387.10x = 1,914.60 × 915.34
4. Step 4: Simplify right side
   1,387.10x = 1,752,509.96
5. Step 5: Solve for x
   x = 1,752,509.96/1,387.10
6. Step 6: Final answer
   x = 1,263.43