Finding the Fourth Proportional to 1,578.18, 2,177.91 and 915.15

Step by Step Solution

1. Step 1: Write the proportion equation
   1,578.18 : 2,177.91 = 915.15 : x
2. Step 2: Convert to fraction form
   1,578.18/2,177.91 = 915.15/x
3. Step 3: Cross multiply
   1,578.18x = 2,177.91 × 915.15
4. Step 4: Simplify right side
   1,578.18x = 1,993,114.34
5. Step 5: Solve for x
   x = 1,993,114.34/1,578.18
6. Step 6: Final answer
   x = 1,262.92