Finding the Fourth Proportional to 1,578.54, 2,178.20 and 870.36

Step by Step Solution

1. Step 1: Write the proportion equation
   1,578.54 : 2,178.20 = 870.36 : x
2. Step 2: Convert to fraction form
   1,578.54/2,178.20 = 870.36/x
3. Step 3: Cross multiply
   1,578.54x = 2,178.20 × 870.36
4. Step 4: Simplify right side
   1,578.54x = 1,895,818.15
5. Step 5: Solve for x
   x = 1,895,818.15/1,578.54
6. Step 6: Final answer
   x = 1,200.99