Finding the Fourth Proportional to 1,387.89, 1,914.39 and 857.03

Step by Step Solution

1. Step 1: Write the proportion equation
   1,387.89 : 1,914.39 = 857.03 : x
2. Step 2: Convert to fraction form
   1,387.89/1,914.39 = 857.03/x
3. Step 3: Cross multiply
   1,387.89x = 1,914.39 × 857.03
4. Step 4: Simplify right side
   1,387.89x = 1,640,680.09
5. Step 5: Solve for x
   x = 1,640,680.09/1,387.89
6. Step 6: Final answer
   x = 1,182.14