Finding the Fourth Proportional to 1,398.47, 1,928.39 and 1,189.31

Step by Step Solution

1. Step 1: Write the proportion equation
   1,398.47 : 1,928.39 = 1,189.31 : x
2. Step 2: Convert to fraction form
   1,398.47/1,928.39 = 1,189.31/x
3. Step 3: Cross multiply
   1,398.47x = 1,928.39 × 1,189.31
4. Step 4: Simplify right side
   1,398.47x = 2,293,437.92
5. Step 5: Solve for x
   x = 2,293,437.92/1,398.47
6. Step 6: Final answer
   x = 1,639.97