Finding the Fourth Proportional to 1,123.70, 1,678.88 and 1,085.42

Step by Step Solution

1. Step 1: Write the proportion equation
   1,123.70 : 1,678.88 = 1,085.42 : x
2. Step 2: Convert to fraction form
   1,123.70/1,678.88 = 1,085.42/x
3. Step 3: Cross multiply
   1,123.70x = 1,678.88 × 1,085.42
4. Step 4: Simplify right side
   1,123.70x = 1,822,289.93
5. Step 5: Solve for x
   x = 1,822,289.93/1,123.70
6. Step 6: Final answer
   x = 1,621.69