Finding the Fourth Proportional to 1,578.43, 2,178.15 and 915.25

Step by Step Solution

1. Step 1: Write the proportion equation
   1,578.43 : 2,178.15 = 915.25 : x
2. Step 2: Convert to fraction form
   1,578.43/2,178.15 = 915.25/x
3. Step 3: Cross multiply
   1,578.43x = 2,178.15 × 915.25
4. Step 4: Simplify right side
   1,578.43x = 1,993,551.79
5. Step 5: Solve for x
   x = 1,993,551.79/1,578.43
6. Step 6: Final answer
   x = 1,263.00