Finding the Fourth Proportional to 1,578.56, 2,178.24 and 915.30

Step by Step Solution

1. Step 1: Write the proportion equation
   1,578.56 : 2,178.24 = 915.30 : x
2. Step 2: Convert to fraction form
   1,578.56/2,178.24 = 915.30/x
3. Step 3: Cross multiply
   1,578.56x = 2,178.24 × 915.30
4. Step 4: Simplify right side
   1,578.56x = 1,993,743.07
5. Step 5: Solve for x
   x = 1,993,743.07/1,578.56
6. Step 6: Final answer
   x = 1,263.01