Finding the Fourth Proportional to 1,389.70, 2,087.31 and 1,340.50

Step by Step Solution

1. Step 1: Write the proportion equation
   1,389.70 : 2,087.31 = 1,340.50 : x
2. Step 2: Convert to fraction form
   1,389.70/2,087.31 = 1,340.50/x
3. Step 3: Cross multiply
   1,389.70x = 2,087.31 × 1,340.50
4. Step 4: Simplify right side
   1,389.70x = 2,798,039.06
5. Step 5: Solve for x
   x = 2,798,039.06/1,389.70
6. Step 6: Final answer
   x = 2,013.41