Finding the Fourth Proportional to 2,020.61, 2,787.19 and 1,390.05

Step by Step Solution

1. Step 1: Write the proportion equation
   2,020.61 : 2,787.19 = 1,390.05 : x
2. Step 2: Convert to fraction form
   2,020.61/2,787.19 = 1,390.05/x
3. Step 3: Cross multiply
   2,020.61x = 2,787.19 × 1,390.05
4. Step 4: Simplify right side
   2,020.61x = 3,874,333.46
5. Step 5: Solve for x
   x = 3,874,333.46/2,020.61
6. Step 6: Final answer
   x = 1,917.41