Finding the Fourth Proportional to 1,123.81, 1,683.42 and 916.31

Step by Step Solution

1. Step 1: Write the proportion equation
   1,123.81 : 1,683.42 = 916.31 : x
2. Step 2: Convert to fraction form
   1,123.81/1,683.42 = 916.31/x
3. Step 3: Cross multiply
   1,123.81x = 1,683.42 × 916.31
4. Step 4: Simplify right side
   1,123.81x = 1,542,535.35
5. Step 5: Solve for x
   x = 1,542,535.35/1,123.81
6. Step 6: Final answer
   x = 1,372.60