Finding the Fourth Proportional to 1,578.58, 2,178.45 and 915.83

Step by Step Solution

1. Step 1: Write the proportion equation
   1,578.58 : 2,178.45 = 915.83 : x
2. Step 2: Convert to fraction form
   1,578.58/2,178.45 = 915.83/x
3. Step 3: Cross multiply
   1,578.58x = 2,178.45 × 915.83
4. Step 4: Simplify right side
   1,578.58x = 1,995,089.86
5. Step 5: Solve for x
   x = 1,995,089.86/1,578.58
6. Step 6: Final answer
   x = 1,263.85