Finding the Fourth Proportional to 1,171.80, 1,616.76 and 840.78

Step by Step Solution

1. Step 1: Write the proportion equation
   1,171.80 : 1,616.76 = 840.78 : x
2. Step 2: Convert to fraction form
   1,171.80/1,616.76 = 840.78/x
3. Step 3: Cross multiply
   1,171.80x = 1,616.76 × 840.78
4. Step 4: Simplify right side
   1,171.80x = 1,359,339.47
5. Step 5: Solve for x
   x = 1,359,339.47/1,171.80
6. Step 6: Final answer
   x = 1,160.04