Finding the Fourth Proportional to 1,399.89, 1,931.16 and 840.09

Step by Step Solution

1. Step 1: Write the proportion equation
   1,399.89 : 1,931.16 = 840.09 : x
2. Step 2: Convert to fraction form
   1,399.89/1,931.16 = 840.09/x
3. Step 3: Cross multiply
   1,399.89x = 1,931.16 × 840.09
4. Step 4: Simplify right side
   1,399.89x = 1,622,348.20
5. Step 5: Solve for x
   x = 1,622,348.20/1,399.89
6. Step 6: Final answer
   x = 1,158.91