Finding the Fourth Proportional to 1,399.55, 1,930.82 and 840.05

Step by Step Solution

1. Step 1: Write the proportion equation
   1,399.55 : 1,930.82 = 840.05 : x
2. Step 2: Convert to fraction form
   1,399.55/1,930.82 = 840.05/x
3. Step 3: Cross multiply
   1,399.55x = 1,930.82 × 840.05
4. Step 4: Simplify right side
   1,399.55x = 1,621,971.49
5. Step 5: Solve for x
   x = 1,621,971.49/1,399.55
6. Step 6: Final answer
   x = 1,158.93