Finding the Fourth Proportional to 1,390.84, 2,083.52 and 870.55

Step by Step Solution

1. Step 1: Write the proportion equation
   1,390.84 : 2,083.52 = 870.55 : x
2. Step 2: Convert to fraction form
   1,390.84/2,083.52 = 870.55/x
3. Step 3: Cross multiply
   1,390.84x = 2,083.52 × 870.55
4. Step 4: Simplify right side
   1,390.84x = 1,813,805.30
5. Step 5: Solve for x
   x = 1,813,805.30/1,390.84
6. Step 6: Final answer
   x = 1,304.11