Finding the Fourth Proportional to 3,123.20, 4,685.40 and 931.88

Step by Step Solution

1. Step 1: Write the proportion equation
   3,123.20 : 4,685.40 = 931.88 : x
2. Step 2: Convert to fraction form
   3,123.20/4,685.40 = 931.88/x
3. Step 3: Cross multiply
   3,123.20x = 4,685.40 × 931.88
4. Step 4: Simplify right side
   3,123.20x = 4,366,230.55
5. Step 5: Solve for x
   x = 4,366,230.55/3,123.20
6. Step 6: Final answer
   x = 1,398.00