Finding the Fourth Proportional to 5,123.72, 7,685.76 and 1,661

Step by Step Solution

1. Step 1: Write the proportion equation
   5,123.72 : 7,685.76 = 1,661 : x
2. Step 2: Convert to fraction form
   5,123.72/7,685.76 = 1,661/x
3. Step 3: Cross multiply
   5,123.72x = 7,685.76 × 1,661
4. Step 4: Simplify right side
   5,123.72x = 12,766,047.36
5. Step 5: Solve for x
   x = 12,766,047.36/5,123.72
6. Step 6: Final answer
   x = 2,491.56