Finding the Fourth Proportional to 1,389.73, 1,913.75 and 1,242.31

Step by Step Solution

1. Step 1: Write the proportion equation
   1,389.73 : 1,913.75 = 1,242.31 : x
2. Step 2: Convert to fraction form
   1,389.73/1,913.75 = 1,242.31/x
3. Step 3: Cross multiply
   1,389.73x = 1,913.75 × 1,242.31
4. Step 4: Simplify right side
   1,389.73x = 2,377,464.55
5. Step 5: Solve for x
   x = 2,377,464.55/1,389.73
6. Step 6: Final answer
   x = 1,710.74