Finding the Fourth Proportional to 1,578.81, 2,178.89 and 870.79

Step by Step Solution

1. Step 1: Write the proportion equation
   1,578.81 : 2,178.89 = 870.79 : x
2. Step 2: Convert to fraction form
   1,578.81/2,178.89 = 870.79/x
3. Step 3: Cross multiply
   1,578.81x = 2,178.89 × 870.79
4. Step 4: Simplify right side
   1,578.81x = 1,897,355.62
5. Step 5: Solve for x
   x = 1,897,355.62/1,578.81
6. Step 6: Final answer
   x = 1,201.76