Finding the Fourth Proportional to 1,578.42, 2,178.17 and 915.23

Step by Step Solution

1. Step 1: Write the proportion equation
   1,578.42 : 2,178.17 = 915.23 : x
2. Step 2: Convert to fraction form
   1,578.42/2,178.17 = 915.23/x
3. Step 3: Cross multiply
   1,578.42x = 2,178.17 × 915.23
4. Step 4: Simplify right side
   1,578.42x = 1,993,515.64
5. Step 5: Solve for x
   x = 1,993,515.64/1,578.42
6. Step 6: Final answer
   x = 1,262.99