Finding the Fourth Proportional to 2,123.56, 2,930.21 and 1,239.20

Step by Step Solution

1. Step 1: Write the proportion equation
   2,123.56 : 2,930.21 = 1,239.20 : x
2. Step 2: Convert to fraction form
   2,123.56/2,930.21 = 1,239.20/x
3. Step 3: Cross multiply
   2,123.56x = 2,930.21 × 1,239.20
4. Step 4: Simplify right side
   2,123.56x = 3,631,095.38
5. Step 5: Solve for x
   x = 3,631,095.38/2,123.56
6. Step 6: Final answer
   x = 1,709.91