Finding the Fourth Proportional to 1,578.69, 2,178.43 and 915.30

Step by Step Solution

1. Step 1: Write the proportion equation
   1,578.69 : 2,178.43 = 915.30 : x
2. Step 2: Convert to fraction form
   1,578.69/2,178.43 = 915.30/x
3. Step 3: Cross multiply
   1,578.69x = 2,178.43 × 915.30
4. Step 4: Simplify right side
   1,578.69x = 1,993,914.69
5. Step 5: Solve for x
   x = 1,993,914.69/1,578.69
6. Step 6: Final answer
   x = 1,263.02