Finding the Fourth Proportional to 1,386.96, 1,914.74 and 915.18

Step by Step Solution

1. Step 1: Write the proportion equation
   1,386.96 : 1,914.74 = 915.18 : x
2. Step 2: Convert to fraction form
   1,386.96/1,914.74 = 915.18/x
3. Step 3: Cross multiply
   1,386.96x = 1,914.74 × 915.18
4. Step 4: Simplify right side
   1,386.96x = 1,752,331.75
5. Step 5: Solve for x
   x = 1,752,331.75/1,386.96
6. Step 6: Final answer
   x = 1,263.43